R v Darcy (No. 9)

[2022] NSWSC 135

Supreme Court

New South Wales

Medium Neutral Citation:

R v Darcy (No. 9) [2022] NSWSC 135

Hearing dates:

22 October 2021

Date of orders:

21 February 2022

Decision date:

21 February 2022

Jurisdiction:

Common Law

Before:

Lonergan J

Decision:

For the offence of the murder of Mathew John Dunbar, I sentence you to a term of imprisonment of 40 years, comprising a non-parole period of 30 years, commencing on 18 November 2017 and ending on 17 November 2047, with a balance term of 10 years ending on 17 November 2057. You are eligible for release on parole on 17 November 2047.

Catchwords:

SENTENCE – murder – conviction after trial – offence committed in the home – significant degree of planning – set up to make the murder appear to be suicide - domestic violence offence – offence in high range of objective seriousness - no remorse – prospects of rehabilitation unfavourable given continuing denial of responsibility – whether a life sentence should be imposed – community interest in protection and specific deterrence satisfied by lesser sentence considering age of offender at earliest release date – life sentence not imposed

Legislation Cited:

Crimes Act 1900 (NSW), s 18(1)

Crimes (High Risk Offenders) Act 2006(NSW)

Crimes (Sentencing Procedure) Act 1999 (NSW), ss 3A, 21A, 54A & 61

Cases Cited:

CC v R; R v CC [2021] NSWCCA 71

Munda v Western Australia (2013) 249 CLR 600;

229 A Crim R 354; [2013] HCA 38

R v Dawes [2004] NSWCCA 363

R v Morabito (1992) 62 A Crim R 82

R v Sean Lee King [2013] NSWSC 801

Rogerson v R; McNamara v R [2021] NSWCCA 160

Category:

Sentence

Parties:

Regina (Crown)
Natasha Beth Darcy (Offender)

Representation:

Counsel:
B Hatfield (Crown)
J Manuell SC / N Broadbent (Offender)

Solicitors:
Office of the Director of Public Prosecutions (NSW) (Crown)
Randall Legal (Offender)

File Number(s):

2017/349418

Publication restriction:

Nil

remarks on sentence

1. Natasha Darcy met Mathew John Dunbar in 2014. A kind man, generous to a fault, he wanted to share his love and good fortune with a partner whom he could provide for, care for and cherish. He wanted that person to be Natasha Darcy. He provided a home for her and her three children, money for what they needed, generous gifts and his attention, his time, his love and support.

2. On 2 August 2017, having successfully harangued Mathew to change his Will in 2015 providing for her to be the sole beneficiary of his large and valuable farming property in Walcha, presciently called “Pandora”, Natasha Darcy murdered him.

3. She did this by sedating him with a mix of drugs and then placing a helium gas cylinder by the bedside and an exit bag arrangement over his head, fastened around his neck with elastic. She then turned on the helium gas to kill him, staging the scene to look like suicide. He was 42 years old.

4. Ms Darcy’s iPhone and computer search records reveal that this murder had been months in the planning, but she denied that she had been involved, acting out an elaborate, clumsy and ugly ruse that Mathew had been “troubled” and that he had taken his own life.

5. She was arrested on 18 November 2017 and has remained in custody since that day. On 29 March 2021 the trial commenced before a jury initially of 12 and then 11 and me. On 15 June 2021 the jury found the offender guilty of Mathew’s murder. She now stands to be sentenced for that offence.

6. The maximum sentence for murder is life imprisonment and there is a standard non-parole period of 20 years.

7. Section 61(1) of the Crimes (Sentencing Procedure) Act 1999 (NSW) provides that a Court is to impose a sentence of imprisonment for life on a person who is convicted of murder if the Court is satisfied that the level of culpability involved in the commission of the offence is so extreme that the community interest in retribution, punishment, community protection and deterrence can only be met through the imposition of that sentence.

8. The Crown submits in the present case that the murder here is in the worst category and that a life sentence should be imposed.

The facts of the offending

9. As stated by Bellew J in R v Sean Lee King [2013] NSWSC 801 at [14]:

“In determining the circumstances of the offending, any factual findings I make must be consistent with the verdict of the jury. In particular, I must accept such facts as are established by that verdict, and I must not determine any factual issue in a way which is inconsistent with it (see R v Isaacs (1997) 41 NSWLR 374). The Crown bears the onus of satisfying me, beyond reasonable doubt, of any finding of fact against the offender. The offender bears the onus of proving factual matters in mitigation on the balance of probabilities”.

10. The following facts I find established on the evidence.

11. The relationship between the offender and Mathew was initiated by her by online contact in late 2014.

12. During the relationship, the offender had no income or assets and had significant debt. She relied upon Mathew to provide for her financially.

13. In October 2016 the offender and her three children moved into “Pandora” with Mathew.

14. The offender had persuaded Mathew to change his Will so that she was the sole beneficiary of his estate. On 13 May 2015 he formalised this position which had the effect of leaving “Pandora” entirely to her in the event of his death.

15. At the time of the murder, “Pandora” was valued at approximately $3.4 million.

16. From early February 2017 to early April 2017 on many different days, using both her mobile phone and the mac computer located in the office at “Pandora”, the offender made a number of topic searches about and including “poisonous mushrooms”, “poisonous fungi”, “spider venom” and “dangerous plants”.

17. The Crown asserts that this evidence demonstrates beyond reasonable doubt that those searches were to find natural items that would be capable of being utilised by the offender to kill Mathew and make it look like misadventure. Whilst that may have been the purpose, I cannot conclude beyond reasonable doubt that it was, and so I put those searches to one side.

18. From early March 2017 to late April 2017 the offender researched the human anatomy and injections into parts of the body that would be capable of causing death. Examples of those searches include “spinal tap”, “epidural”, “air injected into vein”, “inject air into spine”, “lumbar puncture how far”, “depth of spinal cord”, “spine meets brain”, “spinal injections” and “stabbed in the brain”.

19. On 23 March 2017 the offender searched amongst other similar wordings, “can police see websutes” (sic) and “if police have your mobile can they see websites”.

20. On 10 April 2017 the offender began researching “suicide”, “drugs” and “drugs used in suicide”.

21. Around 11 April 2017 Mathew’s friend Craig Hoy committed suicide.

22. From 18 April to 13 June 2017 the offender searched the following: “how to commit suicide”, “food processor recipes”, “suicide methods”, “how many tablets suicide”, “valium suicide”, “sedative suicide”, “cyanide”, “cyanide pill”, “ecstasy suicide”, “overdose pain killers”, “catapress overdose”, “lethal dose of clonidine”, “ketamine”, “drugs for suicide” and “medicine for death”.

23. Around this time the offender began making statements to others claiming Mathew had mental and physical problems in order to lay a false trail of evidence to explain his death that she was planning. She told Laura McKnight (who did not know Mathew) that Mathew had about 6 months to live due to terminal brain injury/tumour and that he had advised medical staff not to resuscitate him. On 15 April 2017 she told local friend Belinder Wauch that Mathew was “really depressed lately” and “with Craig’s death he’s even worse”.

24. On 13 June 2017, following an argument initiated by the offender about money Mathew had recently given to an ex-girlfriend, Mathew threatened to commit suicide and was voluntarily admitted to Banksia Mental Health Inpatient Unit at Tamworth Hospital (Banksia) on 13 June 2017 until 15 June 2017. In the weeks prior to this incident, the offender had been emotionally manipulating and “gaslighting” the deceased including by making reference to the rafters in the shed “not being high enough to hang himself from”.

25. Whilst Mathew was admitted to Banksia, the offender provided a false history to his treating doctors regarding a history of depression and recent behaviour, continuing to lay a false trail.

26. From this point on, emboldened by having an independent basis for the deceased’s asserted suicidality, the offender continued her research into possible methods to use to cause Mathew’s death by means that could be made to look like suicide.

27. On 14 June 2017, whilst Mathew was admitted to Banksia having just been prescribed sertraline, the offender was in his home researching methods to cause his death, including “antidepressant types”, “sertraline”, “sertraline overdose”, “seroquel”, “seroquel suicide”, “seroquel overdose”, “seroquel overdose with alcohol”, and “taking seroquel after drinking”.

28. On 17 June 2017, whilst the offender was away with her daughter for a horse event, the offender researched on her iPhone the drug acepromazine and related topics. She searched, “ace horse sedative”, “is aceptomaxine human” (sic), “ace dose”, “ibm body weight”, “ibm horse body weight”, “buttocks”, “inter muscle injection”, “how to give an intramuscular injection”, “muscles”, “buttocks” and “inter muscle”.

29. On 18 June 2017 the offender searched “muscles inback”, and when back at “Pandora” searched on Mathew’s phone, “how long until ace works”, “horse ace”, “ace injection”, “ace promazine under”, “ace promazine sub”, and “ace humans”.

30. On 19 June 2017, within 48 hours of having first researched acepromazine on her iPhone, the offender called the Walcha Vet Clinic and requested a “ram sedative” saying that Mathew required it for his rams. Her request was declined.

31. On 19 and 20 June 2017, the offender searched “Doug Edlington Vet” and attempted to contact that veterinarian. This was another attempt to obtain acepromazine.

32. On 20 June 2017, scripts were filled for clonidine (for her son) and sertraline (for Mathew) from Kings Pharmacy. Later that day, the offender searched “mus les” (sic), “buttocks” and “upper leg”.

33. At 11:21pm on 20 June 2017, Mathew’s iPhone was used to send to the offender an SMS which read “I’m sorry beautiful lady for everything I’ve put you through you deserve better than this”.

34. The Crown submitted that I should find that this text message was in fact sent by the offender on Mathew’s phone as a pretend suicide note. It may have been, but it is relatively non-specific and I cannot find beyond reasonable doubt that it was a fake suicide note created by the offender and so I put it to one side.

35. On 21 June 2017, police who attended “Pandora” to carry out a welfare check, observed Mathew to be extremely pale, unsteady on his feet, and very dry around his mouth. He was unable to speak intelligibly, slurring his words. The evidence of Mr Farrar, Pharmacologist, was that this presentation was consistent with a clonidine or sertraline overdose.

36. On 22 June, Mathew went to see his GP Dr Allen who diagnosed strep throat infection serious enough to require a penicillin injection.

37. On 24 June 2017, the offender sent a text message to Colin Crossman that said: “I think that Mat took his whole month of antidepressants, that’s why he’s so sick. Will it do permanent damage? Don’t tell anyone. I don’t want to have him committed again.” Mr Crossman replied, “I don’t know. Ring the doctor.” The offender replied, “Ok, I’ll call Banksia”. The offender did not call Banksia nor alert any medical practitioner.

38. On 25 June 2017, the offender searched “how to comit murder” (sic) on her iPhone.

39. On 26 June, Mathew called Dr Allen. He explained that he had filled the script for sertraline from 20 June, but had misplaced the medication, and asked for another script.

40. The Crown submitted that looking at these events between 19 June and 26 June, I should consider that the sertraline had not been lost but had been taken by the offender and administered to Mathew without his knowledge with the intention of causing him to overdose.

41. I accept that the offender drugged Mathew some time between his return home (after he had attended the vet and the pharmacy in Walcha on the afternoon of 20 June) and that when the police visited Pandora on the afternoon of 21 June. This would provide an explanation for his presentation on 21 June as observed by the two police officers. Dr Allen’s diagnosis of strep throat on 22 June, even if a correct diagnosis, does not exclude that the offender subjected Mathew to a surreptitious excess dosing of sertraline and or clonidine.

42. Over the next few days, the offender stepped up her search for acepromazine. On 26 June 2017, she called North Hill Veterinary Clinic in Armidale and attempted to obtain acepromazine using false details. Her request was declined.

43. On 27 June 2017, the offender called Creeklands Vet Clinic in Armidale. Armidale is a town which is approximately a 44 minute drive away from Walcha. She later that day searched “acp 10mg/10ml”, “acepromazine human”, “acepromazine suicide”, and “ace injectable dose”, “acepromazine dose humans”, “acepromazine human overdose”, and “acepromazine inject”.

44. On 28 June 2017, the offender attended Creeklands Vet Clinic and purchased a 100mL bottle of 10mg/mL Acepromazine and an 18-gauge 1 inch monojet needle, in cash, and under a false name and address.

45. On 1 July 2017, the offender searched “ACP injection 10mg/ml”, acp 2 injection”, “acp tablets for humans”, “acepromazine mellow yellow”, “what would acepromazine do to a human”, “acp suicide”, “acp injection suicide”. “acepromazine injection suicide”, “acp inj humans”, “acepromazine”, “acepromazine murder”, “acepromazine humans”, “acepromazine”, “acepromazine suicide dose”, and “acepromazine overdose in humans”.

46. On 3 July 2017, the offender searched “leg muscles” and “leg muscle injection sites”, and on 4 July 2017, at 1:03am, she searched on her phone “suicide porm” (sic). These searches were made as part of planning to stage Mathew’s death.

47. On 7 July 2017, the offender used Mathew’s mobile phone to search “can you inject valium”, “suicide poem”, “muscles for injection”, and “calf muscle”.

48. On 8 July 2017, the offender searched on her mobile phone, “no urine 24 hours”, “what happens if you don’t urinate”, “what happens if you don’t urinate coma”, “don’t urinate unconscious”, “can’t wee unconscious”, “fainting and urinating on yourself”, “acepromazine humans”, “acepromazine mellow yellow”, and “acepromazine overdose”.

49. I have concluded that the offender, without Mathew’s knowledge, sedated him and injected acepromazine into his calf. When he regained consciousness, over a day later, the offender told Mathew that he had “passed out whilst out on a walk”. This history was repeated to the doctors who investigated and treated him. Mathew’s calf was swollen and infected. Scans showed that there was a haematoma in the calf. The doctors investigating were unsure of the origin of the pathology and presentation of Mathew’s leg.

50. I am satisfied that an injection of acepromazine was administered by the offender into Mathew’s calf and caused Mathew’s calf condition. The fact that doctors treating him at the time hazarded guesses about the origin of the unusual presentation does not inform this issue in a way that raises a reasonable doubt. The offender is not to be punished for this conduct separately, but it is conduct relevant to the extent of planning and persistence in relation to the murder she successfully completed on 2 August.

51. From 10 to 18 July 2017, Mathew remained in Walcha and Tamworth Hospitals for investigation and treatment of his calf. He was provided with endone and temazepam during his admission. Whilst he was in hospital, on two separate days the offender searched “oxycontin”, “oxycontin suicide”, “can you inject oxynorm”, “can you inject oxycontin”, “endone” and “how to inject endome” (sic), “oxycontin suicide”, “lethal dose of oxycodone 200 lb male”, “oyxcontin overdose stories”, “Hydrocodone/Oxycodone Overdoes”, “oxycontin murder”, “oxycontin murder – suspect pleads guilty”, “oxycontin taste”, “when you eat an oxycontin 80 is it supposed to have a sweet taste?”, “temazepam”, “temazepam taste”, “valium taste”, “Phenergan”, “Phenergan overdose”, “phenergan injection”, “promethazine lethal dose”. Endone is another name for oxycontin. This replicates the pattern of behaviour by the offender of searching for ways to kill Mathew using things that are or will likely be available at Pandora.

52. On about 20 July 2017, the offender told Michelle Bray that she was “glad there were no drugs in the house as Mathew had said to her if there had been drugs in the house he would have overdosed”. She asked Ms Bray whether he could overdose on antidepressants and Ms Bray told her that would just make him sleepy. Michelle Bray is a nurse. I find that this conversation had the dual purpose of laying a false trail, planting fresh seeds for potential “suicide” by Mathew as well as finding out from someone who would know, what antidepressants might accomplish in terms of the offender’s ongoing plan to kill Mathew.

53. On 20 July 2017, the offender searched “sedazine paste”, “sedazine paste tastte” (sic), “sedazine acp paste”, sedazine paste dose”, and “acepromazine maleate”. Sedazine is a vet medicine used to sedate horses.

54. On 21 July 2017, the offender used her phone to search “arsenic”.

55. On 23 July 2017, the offender searched on her phone the following: “oxycontin murder – suspect pleads guilty”, “intubating”, “feeding tube”, “suicide”, “oxycodone suicide”, “Ritalin suicide overdose”, “can you die from taking Ritalin?”, “Concerta 27mg”, “concerta suicide”, “Concerta and suicide”, “concerta suicidal ideation”, “suicide concerts”, “suicide concerta”, “suicide Ritalin overdose”, “lethal dose of Ritalin”, “suicide pills”, “painless methods suicide”, and “where to buy drugs”. Concerta also known as Ritalin was available at Pandora because it had been prescribed for one of the offender’s children.

56. On 24 July 2017 Mathew attended Tamworth Hospital because of the ongoing problems with his calf. An ultrasound was performed which showed “calf myocitis” an inflammation in the calf muscle - with a small possible abscess. DVT was excluded. He was provided with endone and temazepam.

57. On 24 July 2017, the offender searched “getting avein” (sic), “stroke murder”, “murder by stroke”, “murder by inducing heart attack” and “99 undetectable poisons”.

58. On 25 July, the offender travelled to Armidale and purchased from a Ms McKnight a full box of paliperidone (28 pills) and 4 pills of seroquel (300mg) each, having requested from Ms McKnight: “Anything that will make him sleep is great. I’ll take it all”.

59. Whilst in Armidale, the offender purchased 4 x 23g needles and 2 x 10mL syringes from Creeklands Vet Clinic under a false name “Natasha Daley”.

60. That same day, the offender used her phone to search, “paliperidone suicide”, “can you inject paliperidone”, “can you inject paliperidone tablets”, “overdose paliperidone”, “seroquel”, “seroquel overdose”, “how many seroquel to overdose and die”.

61. On 26 July 2017, the offender searched “inserting feeding tube”, “mouth tube”, “mouth freeding tube” (sic), “respiratory stomack” (sic), “respiratory system”, “stomach respiratory problems”, “gastrointestinal tract”, “stomach and respiratory system”, “what stops lungs getting food”, “upper organs of the body”, “inject Seroquel”, “iv hydrogen peroxide”, “hydrogen peroxide therapy dosage”, “what happens if you inject hydrogen peroxide”, “murder via iv”, “murder by injection”, and “inject iv to death”.

62. On 27 July 2017, the offender searched “suicide by injecting”, “how does potassium chloride stop the heart”, “how much potassium chloride is lethal”, “what would be the lethal dose of potassium ingested in grs (for a human)?”, “potassium overdose how much”, “lethal dose of potassium”, “where to get potassium”, “where to get potassium chloride”, “potassium chloride”, “suicide by hydrogen”, “suicide by hydrogen peroxide”, “suicide intravenous injection”, “what drugs are best for suicide”, “injecting air iv”, “potassium chloride”, “hydrogen peroxide”, “suicide nvia injection” (sic), “iv serequel” (sic), “drug overdose”, “drug overdose via nt tube” (sic), “how to insert ng tube”, “how to insert ng tube in unconscious patient”, “gastrointestinal tract”, “feeding tube mouth”, “feeding tube through mouth”, “why does food lungs”, “how does food know which pipe to go down?”, “how does food go down the right pipe?”, “put feeding tube through mouth”, “hydrogen peroxide murder”, “hydrogen peroxide injection murder”, “what would happen if you injected hydrogen peroxide into your bloodstre”, “imjection for suicide” (sic) and “potassium chloride”.

10. On 28 July 2017, the offender searched “death by injection”, “murder by injection”, “injection for suicide”. She then travelled to Dorrigo with her daughter and her daughter’s friend. Whilst at Dorrigo, the offender searched, “suicide pills”, “suicide by pills”, “paliperidone”, “suicide paliperidone”, “highest dose of invega”, “overdose paliperidone”, “invega overdosage”, “paliperidone suicide”, “suicide paliperidone”, “stomach pump”, “acpromezine”, “phenothiazine”, “successful suivide”, “seroquel and phe”, “suicide by pills”, “seroquel”, “paliperidone”, “paliperidone and quetiapine” (sic), “paliperidone and acepromazine”, “suicide drugs used”, “drugs on auto”, “suicide medicinr” (sic), “suicide bag” and “is xanax a barbiturate”.

11. On 29 July 2017, the offender searched “suivide hydrogen” (sic), “suivide hydrogen peroxide”, “suicide peroxide”, “suicide by injecting peroxide”, “how much hydrogen to kill”, “hydrogen peroxide.”, “hydrogen peroxide iv”, “murder via imjection” (sic) and “what to inject to kill yourself”.

12. At about 2:40pm on 29 July 2017, the offender came across a website which instructed how to commit suicide and recommended helium asphyxiation as the best method. The offender then searched “suicide helium”, “spotlight helium”, “gas bottle” and “suicide pronan” (sic).

13. Later that evening, the offender searched, “delete all web history”, “how long Telstra web history”, “when suicide home crimescene”, “suicide house”, ‘suicide house crimescene”, ‘crimescene suicide”, “after suicide is house a crime scene”, “after a suicide is there a crime scene?”, “how long after suicide is house crime scene”, “bbq gas”, “lpg” and “suicide propan” (sic).

14. On this day, the offender formulated in her mind a specific plan to murder the deceased by staging his death as a suicide by helium asphyxiation, and over the following days in furtherance of that plan she continued to search specific information, items and techniques to complete that plan successfully.

15. On 30 July 2017 in the afternoon, the offender returned to Pandora and searched, “normison”, “seroquel”, “benzodiazepine”, “benzodiazepine and quetiapine”, “quetiapine vs diazep”, “gas boytle” (sic), “suicide bag over head”, “suicide using plastic bag and gas”, “exit bag and prop”, “exit bag and gas”, “suicide bag and gas”, “suicide gas”, “suicide propane gas asphyxiation”, “suicide bag propane”, “suicide helium”, “suicide propane or helium”, “propane or helium”, “helium hire tamworth”, “cubic feet to meters squared”, “suicide helium”, “suicide helium or propane”, “tubing”, and “tubing pipe”.

16. On 31 July 2017, at “Pandora”, between 1:15pm and 1:20pm, the offender used her phone to search “suicide bag” and “helium hire Tamworth”. She then used the Mac Computer to search “helium gas tamworth” and “helium uses”. At the time she was doing so, Mathew was attempting to call her and she did not answer.

17. At 2:15pm, the offender used the landline at “Pandora” to call Supagas. She spoke to an employee there, Emma Worrell, and requested rental of a 3.5m3 cylinder of helium, saying it was for an event she was holding, and advising that it would be collected by Mathew the following day.

18. Also on that day, the offender requested Colin Crossman to obtain more clonidine for their son.

19. Later that evening, the offender searched, “can police see past web history”, “can your internet history be tracked by internet provider”, “can you internet history iphonebe tracked by internet provider” (sic), “how long do internet providers keep history”, “helium tamworth” and “suicide bag”.

20. On 1 August, at about 9:47am, the offender and Mathew attended Tamworth Base Hospital together for a consultation with the orthapedic department about Mathew’s calf. Whilst there, the offender searched on her phone “elgass” and “helium hire tamworth”. She took two screenshots of a 3.5m3 helium cylinder and sent them via MMS to Mathew’s phone.

21. At about 11:35am, the offender attended Supagas at West Tamworth with Mathew. She parked outside and Mathew entered the store and paid for and collected the helium.

22. They together then attended the Gusto Café at Peel Street, Tamworth. Whilst Mathew was inside the café ordering, the offender sat at a table outside and searched on her mobile phone the following: “DIY exit bag instructions” and watched parts, if not all, of several videos on YouTube visually demonstrating the technique(s) required to successfully commit suicide using helium gas and an exit bag.

23. She continued to search the manner in which she would murder Mathew even after he had returned to the table and sat opposite her. She searched “suicide bag”, “suicide bag regulator”, “suicide bag how to connect”, “suicide bag connect helium” and “how to use helium” on her phone whilst he was on his phone updating friends about his visit to the doctor.

24. The offender and Mathew returned home to Pandora that afternoon. The offender prepared a simple dinner for the family and she and Mathew shared a bottle of red wine.

25. At a time between 7:00pm and 1:00am, the offender prepared a drink for Mathew in a Magic Bullet machine. Without his knowledge, she added clonidine, quetiapine, temazepam, and acepromazine to that drink. She poured the drink into a glass tumbler and provided it to him and he drank it and went to bed soon after. He remained in bed, heavily sedated by the combination of those drugs. Whilst he remained sedated in bed, the offender moved the helium cylinder into the main bedroom and set up the exit bag type apparatus using a plastic bag, a length of white tubing cut from a shower hose in the laundry, black tape and elastic around the bag tightened around Mathew’s neck.

26. The offender staged a suicide scene by disposing of or concealing the blue tilt-valve that was provided by Supagas when they collected the helium cylinder, the acepromazine she had obtained, the seroquel packaging and the temazepam packaging, and leaving the clonidine bottle on the kitchen counter and an empty bottle of clonidine in the bin.

27. At 11:25pm, the offender had a Facebook Messenger conversation with Belinder Wauch.

28. At 12:36am, the offender used Mathew’s phone to search “is helium traceable autopsy” on Google, and browsed the result “Toxicological findings in three cases of suicidal asphyxiation with helium”.

29. In the early hours of 2 August 2017, the offender murdered Mathew by placing the plastic bag over his head whilst he remained sedated, securing it with the elastic, and turning on the helium gas. Those acts caused his death by asphyxiation.

30. She performed those acts with the intention of killing him.

31. At 1:14am, at a time Mathew was most likely already dead, the offender sent an SMS from Mathew’s phone to Colin Crossman comprising in effect a fake suicide note “Tell police to come to house. I don’t want Tash or kids to find me”.

32. At about this time, the offender deleted her phone’s entire internet history.

33. At 2:00am, having not received a response from Colin Crossman, the offender called Triple Zero and falsely claimed to have discovered the “suicide”.

34. The offender maintained that lie (Mathew’s death being a suicide) during the entire police investigation. Throughout four police interviews she told many lies in relation to matters such as Mathew’s mental health, physical health, sexuality, sexual health, relationships, financial position and his ability to run his business.

35. The offender told many lies in an attempt to deceive the investigating police in relation to her knowledge of the contents and effect of Mathew’s Will, ordering the helium, her purchase of the various sedatives and her internet history.

36. The offender continued to research what police could locate on her phone and whether they could access deleted internet history and communications. She went so far as to seek technical information and assistance from Apple Support and Lyonswood Investigations & Forensics about these things. The offender also researched the ability of police to detect clonidine, acepromazine, seroquel and temazepam on autopsy.

37. Following her arrest, whilst bail refused, the offender attempted to bribe Amanda Elderfield to give specific evidence about Mathew in an effort to bolster the “suicide” assertions the offender had made to police. Ms Elderfield ignored this request and came forward to police about it during the trial. This conduct is now the subject of separate charges which are pending. The offender also coached the evidence of her two eldest children.

Sentencing Principles

91. As I have said, the offence of murder is contrary to s 18(1) of the Crimes Act 1900 (NSW) and carries a maximum sentence of life imprisonment and a standard non-parole period of 20 years. A life sentence is to be imposed if the level of culpability involved in the commission of the offence was so extreme that the community interest in retribution, punishment, community protection and deterrence can only be met through the imposition of that sentence.

92. I need to bear in mind the seven purposes of sentencing referred to in s 3A of the Crimes (Sentencing Procedure) Act namely, punishment, prevention, protection, rehabilitation, accountability, denunciation and recognition of harm. I need also to take into account both general and specific deterrence.

93. The purposes of punishment set out in s 3A of the Act are constrained by other sentencing principles including proportionality and totality.

94. The maximum penalty (life) and the relevant non-parole period (20 years) operate as legislative guideposts that inform the exercise of the Court’s sentencing discretion.

95. I am required to make an assessment of where the offence falls within the range of objective seriousness for offences of its kind as part of my sentencing task. I do this without reference to matters personal to the particular offender, but wholly by reference to the nature of the offending.

96. When assessing objective seriousness, the intent of the offender at the time of the offence is relevant, and an intention to kill is a consideration tending towards greater objective seriousness.

97. It has been observed by the courts that it is the responsibility of the Court to protect and preserve human life and to punish those who unlawfully take it: R v Dawes [2004] NSWCCA 363 at [31].

98. This murder was committed in the context of a domestic relationship, and so it attracts particular considerations of general deterrence, denunciation and community protection and must recognise the dignity of the domestic violence victim: Quinn v R [2018] NSWCCA 297 at [243]-[245] citing Munda v Western Australia (2013) 249 CLR 600; 229 A Crim R 354; [2013] HCA 38 at [54]-[55].

The objective seriousness of the offence

99. The Crown submitted that the level of culpability is extreme because of the degree of planning and persistence, the calculated and cold-blooded nature of the killing, the clear intention to kill, the callous disregard for Mathew, the exploitative relationship with him, the purely financial motive and greed and the absence of any relevant mitigating factors.

100. The onus of satisfying the Court that the case falls within s 61(1) of the Act rests on the Crown and the standard of such proof is beyond reasonable doubt.

101. In Rogerson v R; McNamara v R [2021] NSWCCA 160, the Court of Criminal Appeal adopted the approach of Adamson J in CC v R; R v CC [2021] NSWCCA 71 confirming that a two stage approach to s 61(1) is appropriate. The first stage is to assess whether the offence warrants a life sentence and the second is to assess whether a lesser sentence is warranted because of other matters such as remorse, confessions, pleas of guilty and prospects of rehabilitation.

102. Separate to the statute and under the common law, the Court may impose the maximum penalty where the case is considered to be in the worst case category.

103. This is a murder of high objective seriousness.

104. Searches conducted by the offender on her iPhone from April 2017 to the night of the murder indicate perseverant focus on ways to kill. As time passed, the searches became centred around drugs, concepts and ideas that could be manipulated into the appearance of suicide. Emotional abuse and sneaky physical attacks escalated into a more focused and fool proof method to achieve the outcome she desired. The offender was callous, relentless, and heartless in her pursuit to get rid of Mathew who stood between her and the valuable, almost entirely unencumbered property, “Pandora”. Greed was her motive. Deception, lies, and manipulation were glibly applied before and after she killed him. Her lies and methods were stupid, clumsy, and ugly but were sadly successful in achieving Mathew’s death. They were not however good enough to evade detection.

105. I am not however persuaded that the level of culpability is so extreme that the community interest in retribution, punishment, community protection and deterrence can only be met through imposition of a life sentence.

106. Issues of community protection and specific deterrence can be met through the imposition of a very lengthy fixed sentence, with that sentence still reflecting those factors as well as the community’s interest in retribution, punishment and general deterrence.

Aggravating and mitigating factors

107. Section 21A of the Act requires me to take into account certain aggravating and mitigating factors in determining the appropriate sentence. The fact that any such aggravating or mitigating factor is relevant and known to the Court does not require the Court to increase or reduce the sentence for the offence: (21A(5). I have taken the following matters into account in reaching the sentence I have determined.

Aggravating factors – s 21A(2) of the Crimes (Sentencing Procedure) Act

108. The offence involved the offender causing Mathew to take and be affected by sedatives seroquel, acepromazine, temazepam and clonidine. This is an aggravating factor under s 21A(2)(cb).

109. The murder was committed in his home and this is an aggravating factor under s 21A(2)(eb).

110. The offender was on parole at the time for an offence of pervert the course of justice. Because the murder was committed whilst she was on conditional liberty, this too is an aggravating factor: S 21A(2)(j).

111. The murder was committed for financial gain. The offender was already benefiting financially, having moved in with Mathew and him paying her expenses. She manipulated Mathew into changing his Will to make her the sole beneficiary. She killed him motivated by greed. This is an aggravating factor: s 21A(2)(o).

112. Section 21A(1)(c) also allows the Court to take into account any other objective factor that affects the relative seriousness of the offence. The degree of premeditation or planning has long been recognised as a factor in weighing the seriousness of an offence: R v Morabito (1992) 62 A Crim R 82 at [86]. This murder involved a very high degree of planning for well over three months, even if the precise method employed to accomplish it had only featured in her last three days of searches and planning.

Mitigating factors - s 21A(3) of the Crimes (Sentencing Procedure) Act

113. There is little to say by way of mitigating factors. The offender has shown nothing remotely resembling remorse or contrition. Despite being convicted by the jury in June 2021, she maintained to Dr Furst psychiatrist in October 2021 that Mathew had killed himself and that she “should have done more to get him help”. To Dr Pulman who also assessed her in October 2021, the offender stated that she was unwilling to accept the verdict and maintained that she had no involvement in Mathew’s death.

114. I cannot find that the offender is a person of good character given her criminal record which included sentences for imprisonment for in 2009 hitting her husband Colin Crossman on the head with a hammer whilst he slept and setting fire to their house with the admitted aim of obtaining the insurance money, larceny, multiple counts of dishonestly obtain property by deception involving the unauthorised use of the credit card of another man with whom the offender had been in a domestic relationship.

115. I cannot find that she is unlikely to re-offend. Her offending is multi-factorial, opportunistic and driven by money and it is unclear how those factors would dissolve as precipitants for re-offending.

116. Dr Pulman in her report described the offender as having a “complex personality structure” together with generalised anxiety disorder and referred to the need for an intensive period of therapy and that its potential effectiveness is “contingent on her willingness to engage and openly discuss aspects of her life and relationships”, and concluding that “should the offender choose to engage in long term therapy, her prospects for rehabilitation are favourable”.

117. Dr Furst noted the difficulties in making a definitive psychiatric diagnosis retrospectively in individuals who are prone to dishonesty, but felt the offender met the criteria for a diagnosis of a personality disorder with clear tendencies towards dishonesty and manipulation of other people, particularly those closest to her and also the authorities investigating her offences past and recent. He observed that the “prognosis” of people with personality orders is not encouraging as personality disorders tend to be entrenched and enduring conditions. He said that this is evidenced by her pattern of offending and recidivism that dates back to 2009, including re-offending whilst on parole on two occasions.

118. Dr Furst noted the inherent tendencies towards deception and manipulation that include the targeting of intimate partners, means that the greatest future risks for re offending would relate to that rather than instrumental violence towards the wider community. If she continues to deny her offending and denies responsibility for killing Mathew, the prospects of the offender being successfully rehabilitated would be much more limited.

119. I have concluded that the offender’s prospects of rehabilitation are very guarded, given her underlying personality disorder, but most significantly, her ongoing refusal to accept the verdict or acknowledge her killing of Mathew. It is difficult to predict how, when and if that situation will change.

Subjective circumstances of the offender

120. The offender is almost 47 years old. She has three children, one of whom is now an adult. She claims to have been bullied by her two older sisters. She was an average student. She described a history of anxiety back to childhood. She was married three times. She claims to have been sexually abused and assaulted by two of her first husband’s friends in 1997 and that has led to flashbacks and trauma.

121. She claimed to have attempted suicide in 1997 by overdose after the sexual assault. She did not go to hospital or see a doctor initially about this but later did and was prescribed antidepressants.

122. She claims to have had anxiety and panic attacks in her 20s.

123. She married again in 1998 and her first child was born in 2002. She separated from her husband that year.

124. The offender claims that she had anxiety during this time period and was prescribed efexor.

125. The offender was in a relationship with another man in 2003 to 2005 when he left her for another woman. She was 20 weeks pregnant with his child at that time. This was her second child who is now 16.

126. She met Colin Crossman in 2006 and married him in 2007. He is the father of her third child. They separated in 2012. Around that time she pleaded guilty to charges that in 2009 she hit him on the head with a hammer whilst he slept and having poisoned him with prescription medication, left him sleeping in a bedroom which the offender had doused in petrol and set on fire, with the admitted aim of claiming insurance money.

127. She rarely drinks alcohol and denied using drugs.

128. She is currently taking an anti-depressant.

129. She claims to have worked at McDonalds for a few years and then as a vet nurse and for a veterinary pharmaceutical company. She claims to have performed some casual work in Walcha between 2006 and her arrest in 2017 which included waitressing and “working with racehorses”.

120. She was in custody for the 17 months prior to moving in with Mathew in October 2016. She claimed to Dr Pulman and Dr Furst that she had regular discussions with Mathew about suicide and that he was depressed and that she still has flashbacks about “discovering him” with the suicide bag on his head.

121. She described to Dr Furst having symptoms of anxiety in custody and that she felt highly stressed and depressed and “numb” during her trial because “the truth” has not come out.

122. Dr Furst stated that he does not believe that the custodial environment will be any more stressful for her than it would be for the average offender coming before the courts for this type of offence.

123. Dr Pulman noted an incident of asserted self-harm in custody in January 2020 and that the offender had requested counselling and that she had a history of unstable relationships, most likely characterised by conflict due to her traits of dependent personality structure. Dr Pulman noted some ongoing symptoms of anxiety and panic attacks in custody which should be reviewed and monitored during her incarceration.

Comparable sentences

134. I was taken to a series of sentencing decisions that were said to be illustrative or at least informative as to the range of appropriate sentences for the offender. I have read them and taken them into account however this offending has very particular and unusual features - the bizarre, well-demonstrated persistent nature of the planning, the financial motive and the maintenance of the fictitious account despite the jury verdict - which makes it stand apart from other offending of a very broadly similar nature.

Victim Impact Statement

135. I note the victim impact statement from Mathew’s mother, Janet. She states that she feels that she has lost her rock. She remarked upon what a very kind and generous man Mathew was. That was a common theme from his friends and others who gave evidence at the trial. His loss is a significant one to the Walcha community where he was well liked, respected and admired. I convey the Court’s sincere condolences to his mother and his many friends.

Sentence

136. Natasha Darcy, for the offence of the murder of Mathew John Dunbar, I sentence you to a term of imprisonment of 40 years, comprising a non-parole period of 30 years, commencing on 18 November 2017 and ending on 17 November 2047, with a balance term of 10 years ending on 17 November 2057. You are eligible for release on parole on 17 November 2047.

137. I am obliged to tell you of the existence of the Crimes (High Risk Offenders) Act 2006 (NSW), which applies to offences of the type for which you have been sentenced.

138. In summary, this means that the State can apply to the Supreme Court for an order that you be held in detention or receive supervision at the end of your sentence if the Court considers you would be a “high risk offender” who poses an unacceptable risk of committing a further serious violence offence.

**********

Decision last updated: 21 February 2022