DNA Expert
Helen Roebuck is a strongly credentialed and highly regarded forensic DNA expert, trusted within both the legal and scientific communities. She is the most prolific and judgment-published independent DNA expert witness in Australia, with her evidence extensively referenced across various jurisdiction.
Accepting simple and complex briefs, Legal Aid and privately funded – across Australia, New Zealand and select international jurisdictions.
Roebuck Forensics provides robust, independent evaluation of DNA evidence in accordance with current scientific theory and methodology. Expertise includes DNA profiling, biological fluids, STRmix, crime scene examinations, DNA transfer, and bloodstain pattern analysis (BPA). With access to a fully operational forensic laboratory, laboratory examinations and DNA testing, can also be conducted.
With over 25 years’ service to the courts, Ms Roebuck has assessed DNA evidence in thousands of indictable matters, including homicide, sexual assault, drug importation, firearms and explosive device prosecutions.
Helen Roebuck’s expert witness opinion is clear, precise and free from unnecessary complexity, explaining challenging scientific issues in plain, courtroom-ready terms.
DNA Expert witness
Our full spectrum expert forensic consulting service encompasses DNA, bloodstain pattern, biological fluids and STRmix. Drawing upon extensive international and governmental forensic biologist experience at crime scene investigations, laboratory procedures, and highly specialised expert witness evidence presentation before the courts. Roebuck Forensics’ depth of expertise spans the practical, technical, procedural, intellectual and jurisdictional.
With this breadth, we are remarkably well placed to assist the courts with serious matters. Incorporating crime scene assessment, sampling, testing, analysis, and review, such as they may be required, to form the foundation and contribution towards the preparation and presentation of authoritative DNA expert witness testimony.
Contact us
GPO 390 Sydney NSW 2001
02 8089 0226
9am – 5pm GMT + 11hours
Published matters
- WA v Piccioni [2025] – WA District Court
- R v Murphy [2024] – NSW District Court
- LGBTIQ Hate Crimes Inquiry [2023] – NSW
- R v Granaghan [2022] – N Ireland Crown
- R v Perre [2021] – SA Supreme Court
- R v Ke [2019] – NSW District Court
- R v Haouchar [2025] – NSW District Court
- R v Ahmad [2024] – NSW District Court
- Evans v R [2023] – NSW Supreme Court
- R v Tsakirios [2021] – NSW District
- R v Kabbout [2020] – NSW District Court
- R v TAL [2019] – QLD Supreme Court
Early, strategic advice is often informal and does not require a full report.
IN judgement
Firearm possession – DNA transfer – Crime scene officer contamination – Investigator mediated transfer
The judgment, delivered on 3 October 2025, is one of the clearest judicial recognitions to date of the real-world risk posed by investigator-mediated DNA transfer, sometimes referred to simply as forensic contamination.
The prosecution’s case in this firearms possession matter relied heavily on DNA recovered from a Smith & Wesson revolver. The mixed DNA profile supported the accused as a possible contributor with an extremely strong statistical weighting of 100 billion.
My independent review of the audiovisual footage revealed extensive forensic handling failures – reuse of gloves between exhibits, movement of items without contamination control, and large portions of the search conducted off-camera. The handling observed created a clear and substantial risk of investigator-mediated contamination – that is, the inadvertent transfer of DNA from non-inculpatory surfaces within the accused’s storage unit, to the firearm through poor evidence-handling procedures by investigators.
At Voir Dire Judge Astill accepted that, ‘the risk of investigator-mediated contamination is real and necessarily affects the reliability and weight to be attached to the proposed DNA evidence‘ finding that ‘the procedures adopted were not consistent with what was required to avoid investigator-mediated contamination.‘ His Honour specifically stated that ‘Ms Roebuck’s opinion more accurately reflects the significance of secondary transfer … I prefer and adopt her formulation‘.
Ultimately, Judge Astill ruled that, ‘The prejudicial effect of this evidence outweighs the limited probative value it holds. To admit this evidence would result in an unfairness that cannot be cured by direction’
Following exclusion of the DNA evidence, the prosecution discontinued the case. The DNA appeared compelling on paper, but its forensic integrity could not be trusted.
Murder – Bombing – DNA transfer – Crime scene officer contamination – False inclusion
The 1994 fatal bombing of the Adelaide National Crime Association implicating Domenic Perre, is one of Australia’s most sensational and longest running criminal matters.
After initially abandoning the prosecution, advancements in DNA science led to further investigation in 2016.
“ I was instructed by defence counsel to review the forensic DNA evidence pertaining to the cloth, which was purportedly associated with the bomb manufacturing process.
Prosecution intended leading scientific evidence in an effort to prove that Domenic Perre’s DNA was on the cloth.
With a precise interrogation of the DNA profile, I established support for the crime scene officer and Mr Perre’s brother within the profile.
I defined the identification of Domenic Perre within the mixed DNA profile as a false inclusion.
In response to my report and opinion, the prosecution proceeded to trial in 2018 in total absence of this expert DNA evidence.”
Firearms – Drugs supply - DNA transfer – Crime scene officer contamination - Not guilty
Charges alleged that in 2017, the defendant did possess a handgun and a supply quantity of class A drugs, which were seized within a vehicle owned by the defendant, whilst the vehicle was occupied by two other persons.
“ I received instructions to review the DNA expert evidence, along with a file that included body worn camera footage of the initial police vehicle search.
A review of the footage revealed that the crime scene officer did handle various items within the vehicle relevant to the DNA evidence, without thorough anti-contamination procedures.
The DNA sampling of the gun and drugs revealed mixed DNA profiles, of which the accused DNA contributed to pistol grip sample.
Following scrutiny of the relevant evidence, I formed the opinion that the DNA evidence did not contribute significantly to the prosecution version.
The DNA expert forensic evidence was significantly ventilated at trial.
Judgment- Justice Buscombe;
114 : I am not satisfied beyond reasonable doubt that the accused possessed the cocaine.
109: I am unable to place any significant weight upon the findings of the accused’s DNA that was found on the guns grip
(1) Accused found not guilty in relation to all counts on the indictment
Legal Industry Speaking
Our director and forensic DNA expert Helen Roebuck is a regular contributor to the legal profession, accepting invited speaking roles throughout Australia.
DNA evidence is critically relied upon within the criminal justice system like no other forensic science throughout history.
Legal practitioners across the profession, seek knowledge regarding DNA and its contribution to the judicial process, as DNA analysis continues to evolve.
“These speaking events serve the legal profession well, whilst also providing me with valuable engagement that offers a greater understanding of the legal communities further needs and expectations of forensic biology and expert evidence”
legalwise - criminal law conference 2026
- 13 March 2026
New South Wales Legal Aid criminal law conference
- 25 - 27 June 2025
NAAJA - CPD
28 - February 2026
NSW LaW SOCIETY
13 May 2026
Forensic DNA commentary relevant to criminal proceedings
Frequently Asked Questions
What notorious DNA cases has Helen Roebuck worked ?
Helen Roebuck has worked numerous high profile DNA matters since 2001 including; The Family Court Murders, Claremont Serial Murders, NCA Bombing, Lin Family Murders, Madeleine Mccann disappearance, Peter Falconio Murder, The Bicycle Bandit, Scott Austic, Granaghan Bombing, Balzan Police Shooting Inquiry and the LGBTIQ Hate Crimes Inquiry.
How much does a DNA expert cost?
DNA expert Helen Roebuck proffers carefully refined DNA evidence for rates which are comparable to those of a skilled and experienced criminal lawyer.
What is a DNA evidence report?
A DNA expert report authored by Helen Roebuck, will evaluate the crown evidence, biological casefile, relevant documentation and consider the weight of both the prosecution and defence versions. The detailed written expert evidence will follow a clear progression of evidence gathering, evaluation and careful formulation of authoritative opinion.
Does legal Aid funding cover DNA expert evidence?
We are regularly instructed by Legal Aid lawyers and private lawyers with legal aid funding in the service of DNA expert evidence. Our current experience in 2024 is that legal aid funding is not a significant obstacle.
Can we handle matters all over Australia?
Helen Roebuck has extensive and intimate knowledge of the procedures and practices of each and every governmental laboratory throughout Australia. To the extent of familiarity with many of the experts by name and their courtroom manner.
Evidence is regularly provided by Audio Visual Link as well as by way of personal appearance in any state of Australia.
Do we take instruction on DNA matters outside Australia?
Originating from 2001 training at the Forensic Science Service in the UK, Helen Roebuck has been called upon to provide forensic expert opinion in the United Kingdom as well as New Zealand and the United States.