Specialties & Experience
General Specialties:
Forensics
Specialty Focus:
DNA
Education:
BSc Hons Biomedical Sciences - Awarded 2000 Currently undertaking PhD - University of Technology Sydney, Centre for Forensic Science
Years in Practice:
25
Number of cases in the last 4 years:
242
Additional Information
About / Overview:
I am an independent forensic DNA expert witness specialising in the review, interpretation, and evaluation of DNA evidence in criminal matters. I assist criminal defence lawyers by identifying limitations, assumptions, and alternative explanations within DNA evidence, including complex mixed profiles, STRmix analysis, and issues of DNA transfer and contamination.
I provide expert review and reporting for defence teams across Australia and internationally, with particular expertise in complex DNA evidence including mixed DNA profiles, low-level DNA, and issues of transfer, persistence and contamination.
My work focuses on the proper evaluation of DNA evidence in court — not just whose DNA is present, but how it may have been deposited.
Core Expertise:
- Review and interpretation of forensic DNA evidence
- STRmix and probabilistic genotyping analysis
- DNA transfer, persistence and contamination
- Evaluation of low-template and mixed DNA profiles
- Activity level (how did the DNA get there?)
- Sexual assault evidence, including sperm and non-sperm DNA findings
- Bloodstain pattern analysis (BPA)
- Biological fluid identification
What I Do for Lawyers
- Independent review of prosecution DNA evidence
- Identification of limitations, assumptions and alternative explanations
- Case strategy input (early-stage advice)
- Written expert reports (court-ready)
- Conference with counsel
- Court testimony as an expert witness
Experience:
I have worked in forensic DNA analysis since 2001, including within major forensic laboratories and as an independent expert.
I am currently undertaking PhD research in DNA transfer and persistence, with a focus on the interpretation of DNA evidence at the activity level.
I regularly present to criminal lawyers and forensic scientists on DNA evidence, including at CPD seminars and international conferences.
DNA expert witness in following selected Matters:
• Evans V The Queen [2023] – Supreme Court of Appeal NSW
• R v Smith [2022] – District Court Qld
• R v Granaghan [2022] – Crown Court of Northern Ireland
• R v Heeley [2022] - Vic
• Mang v The Queen [2022] – Supreme Court of Appeal Vic
• R v Mooney [2022] – District Court NSW
• R v O’Meara [2022] – District Court TAS
• R v Smith [2021] – District Court Qld
• R v Tsakirios [2021] – District Court NSW
• R v Lukaj [2021] District Court SA
• R v Chol [2021] Vic
• R v Perre [2021] – Supreme Court SA
• R v Chee [2021] – Supreme Court VIC
• R v Dukagjini [2021] – Supreme Court NSW
• R v O’Keefe [2021] – Supreme Court Qld
• R v Beattie [2020] – Supreme Court of Victoria
• R v Byrne [2020] – Supreme Court of Appeal NSW
• R v Kabbout [2020] – District Court NSW
• R v Castro Santafe [2020] – District Court NSW
• Rv Ke [2019] – District court NSW
• R v TAL [2019] – Supreme Court Qld
• Hassan V R [2018] – Supreme Court of Appeal NSW
• JH v R [2017] – Supreme Court of Appeal NSW
• R V Lowe [2016] – Supreme Court South Australia
Why DNA Evidence Requires Careful Evaluation
DNA evidence is often presented as highly persuasive. However, modern DNA techniques can detect extremely small amounts of DNA — including DNA transferred through secondary mechanisms such as handling, contact with objects, or shared environments.
This means:
- The presence of DNA does not necessarily indicate direct contact
- DNA may be transferred without the person being present at the relevant time
- Mixtures and low-level DNA profiles can be open to multiple interpretations
In many cases, the key question is not whether a DNA profile matches an individual, but what that match means in the context of the alleged events.
Common Issues Identified in Casework:
- DNA transfer via intermediaries (secondary transfer)
- Contamination during collection, handling or packaging
- Misinterpretation of mixed DNA profiles
- Overstated likelihood ratios or unclear reporting language
- Failure to consider activity-level propositions
- Assumptions embedded within probabilistic genotyping software
Availability:
Available to provide independent expert advice and reporting, as well as appearing as a DNA expert witness, in criminal matters across Australia and internationally.
Testimonial from Michael Parrella, Criminal Defence Lawyer:
"Our firm engaged Helen to review a prosecution DNA expert report and accompanying police search video. Her task was to determine whether the execution of the search and the handling of exhibits indicated a mass transference event that rendered the DNA evidence unreliable.
From the outset, Helen was highly professional, responsive, and a pleasure to communicate with. She delivered her report promptly and at a very reasonable fee. Her analysis was thorough, precise, and well-reasoned. She agreed with our position and strongly recommended a voir dire to test the admissibility of the DNA evidence. At the hearing, Helen’s opinion was preferred to that of the prosecution expert, and proved pivotal to our successful application to have the DNA evidence excluded.
The DNA evidence was central to the prosecution’s case, and following its exclusion, the ODPP discontinued all charges against our client. Helen is clearly a leader in her field, and it was a privilege to work with her. We look forward to engaging her expertise again in the future."
Testimonial from Gabriel Chipkin, Barrister:
" Helen was an excellent forensic DNA expert witness in a trial I ran in the Supreme Court of the Northern Territory. Helen was able to explain complex DNA concepts in clear and easily understandable terms for the jury, including the mechanics around transference of biological material. Helen made herself available both before and during the trial to answer technical questions and assist me with preparation. Her professionalism, dedication and expert knowledge were instrumental in the presentation of the defence".
Further testimonials, and a full CV can be accessed here: https://roebuckforensics.com.au/helen-roebuck-dna-expert-cv/
Keywords:
forensic DNA expert, DNA expert witness Australia, DNA evidence review, STRmix expert, DNA transfer and persistence
I am an independent forensic DNA expert witness specialising in the review, interpretation, and evaluation of DNA evidence in criminal matters. I assist criminal defence lawyers by identifying limitations, assumptions, and alternative explanations within DNA evidence, including complex mixed profiles, STRmix analysis, and issues of DNA transfer and contamination.
I provide expert review and reporting for defence teams across Australia and internationally, with particular expertise in complex DNA evidence including mixed DNA profiles, low-level DNA, and issues of transfer, persistence and contamination.
My work focuses on the proper evaluation of DNA evidence in court — not just whose DNA is present, but how it may have been deposited.
Core Expertise:
- Review and interpretation of forensic DNA evidence
- STRmix and probabilistic genotyping analysis
- DNA transfer, persistence and contamination
- Evaluation of low-template and mixed DNA profiles
- Activity level (how did the DNA get there?)
- Sexual assault evidence, including sperm and non-sperm DNA findings
- Bloodstain pattern analysis (BPA)
- Biological fluid identification
What I Do for Lawyers
- Independent review of prosecution DNA evidence
- Identification of limitations, assumptions and alternative explanations
- Case strategy input (early-stage advice)
- Written expert reports (court-ready)
- Conference with counsel
- Court testimony as an expert witness
Experience:
I have worked in forensic DNA analysis since 2001, including within major forensic laboratories and as an independent expert.
I am currently undertaking PhD research in DNA transfer and persistence, with a focus on the interpretation of DNA evidence at the activity level.
I regularly present to criminal lawyers and forensic scientists on DNA evidence, including at CPD seminars and international conferences.
DNA expert witness in following selected Matters:
• Evans V The Queen [2023] – Supreme Court of Appeal NSW
• R v Smith [2022] – District Court Qld
• R v Granaghan [2022] – Crown Court of Northern Ireland
• R v Heeley [2022] - Vic
• Mang v The Queen [2022] – Supreme Court of Appeal Vic
• R v Mooney [2022] – District Court NSW
• R v O’Meara [2022] – District Court TAS
• R v Smith [2021] – District Court Qld
• R v Tsakirios [2021] – District Court NSW
• R v Lukaj [2021] District Court SA
• R v Chol [2021] Vic
• R v Perre [2021] – Supreme Court SA
• R v Chee [2021] – Supreme Court VIC
• R v Dukagjini [2021] – Supreme Court NSW
• R v O’Keefe [2021] – Supreme Court Qld
• R v Beattie [2020] – Supreme Court of Victoria
• R v Byrne [2020] – Supreme Court of Appeal NSW
• R v Kabbout [2020] – District Court NSW
• R v Castro Santafe [2020] – District Court NSW
• Rv Ke [2019] – District court NSW
• R v TAL [2019] – Supreme Court Qld
• Hassan V R [2018] – Supreme Court of Appeal NSW
• JH v R [2017] – Supreme Court of Appeal NSW
• R V Lowe [2016] – Supreme Court South Australia
Why DNA Evidence Requires Careful Evaluation
DNA evidence is often presented as highly persuasive. However, modern DNA techniques can detect extremely small amounts of DNA — including DNA transferred through secondary mechanisms such as handling, contact with objects, or shared environments.
This means:
- The presence of DNA does not necessarily indicate direct contact
- DNA may be transferred without the person being present at the relevant time
- Mixtures and low-level DNA profiles can be open to multiple interpretations
In many cases, the key question is not whether a DNA profile matches an individual, but what that match means in the context of the alleged events.
Common Issues Identified in Casework:
- DNA transfer via intermediaries (secondary transfer)
- Contamination during collection, handling or packaging
- Misinterpretation of mixed DNA profiles
- Overstated likelihood ratios or unclear reporting language
- Failure to consider activity-level propositions
- Assumptions embedded within probabilistic genotyping software
Availability:
Available to provide independent expert advice and reporting, as well as appearing as a DNA expert witness, in criminal matters across Australia and internationally.
Testimonial from Michael Parrella, Criminal Defence Lawyer:
"Our firm engaged Helen to review a prosecution DNA expert report and accompanying police search video. Her task was to determine whether the execution of the search and the handling of exhibits indicated a mass transference event that rendered the DNA evidence unreliable.
From the outset, Helen was highly professional, responsive, and a pleasure to communicate with. She delivered her report promptly and at a very reasonable fee. Her analysis was thorough, precise, and well-reasoned. She agreed with our position and strongly recommended a voir dire to test the admissibility of the DNA evidence. At the hearing, Helen’s opinion was preferred to that of the prosecution expert, and proved pivotal to our successful application to have the DNA evidence excluded.
The DNA evidence was central to the prosecution’s case, and following its exclusion, the ODPP discontinued all charges against our client. Helen is clearly a leader in her field, and it was a privilege to work with her. We look forward to engaging her expertise again in the future."
Testimonial from Gabriel Chipkin, Barrister:
" Helen was an excellent forensic DNA expert witness in a trial I ran in the Supreme Court of the Northern Territory. Helen was able to explain complex DNA concepts in clear and easily understandable terms for the jury, including the mechanics around transference of biological material. Helen made herself available both before and during the trial to answer technical questions and assist me with preparation. Her professionalism, dedication and expert knowledge were instrumental in the presentation of the defence".
Further testimonials, and a full CV can be accessed here: https://roebuckforensics.com.au/helen-roebuck-dna-expert-cv/
Keywords:
forensic DNA expert, DNA expert witness Australia, DNA evidence review, STRmix expert, DNA transfer and persistence