Back Home 5 News 5 Sue Petricevic: from forensic scientist, to expert witness, to prosecutor to defence counsel

Sue Petricevic: from forensic scientist, to expert witness, to prosecutor to defence counsel

26 May 2023

| Author: Reweti Kohere

It’s the one question that Sue Petricevic, lawyer and International Skating Union (ISU) judge, won’t answer: who is her all-time favourite figure skater?

“Can’t say. I’m a judge. Can’t say,” she says, shaking her head. “Won’t say, no.” Not even past skaters? “Not going to, not going to. But my favourite discipline is pairs skating. I love the big overhead lifts and the strength of the couples performing together to the music.”

Fair enough. Maintaining impartiality is understandable, whether you’re presiding over a courtroom or from the side of a rink. Having competed in her teens and early 20s, Petricevic turned to judging, working her way up from local and national competitions to big-time international meets.

The Vulcan Chambers barrister gets to travel around the world and has formed enduring friendships with other members of the international skating community. But judging, particularly high-level competitions, can be long and tiring – days can last up to 10 hours, with brief 10 to 15-minute breaks.

“It’s total concentration. When you’re judging a big group of skaters, sitting in the cold in a big auditorium, the judges are nervous and excited too because they want to reflect each skater’s performance correctly and fairly. And the judges themselves are also being checked by another panel,” she says.

“You can’t think about anything else. These assignments are not a walk in the park when you’re sitting there, entering up to 14 marks for each skater in real-time over three or four minutes. That’s a lot of marks.”

Putting her hand up

 Petricevic has another responsibility, chairing the ISU’s disciplinary commission – the first New Zealander to be elected to the position.

A commission member since 2012, she was confirmed chair in 2022 for four years, and works alongside four other elected members (from Slovakia, Germany, the US and Canada), two of whom specialise in figure skating, the other two in speed skating and all of whom are lawyers.

She got involved after attending one of the ISU’s congresses as the vice president of the New Zealand Ice Figure Skating Association. Having heard about the disciplinary commission’s work, “I just put my hand up, I started applying. And then, at the same congress, there was a bit of a constitutional crisis and they asked for nine lawyers from different countries to volunteer and try to sort it out”, she says.

So, again, little old New Zealand, hand up. I probably wasn’t that long out of law school at the time and was chosen. So, I went in and from there, made connections and was able to contribute to that solution. That helped in my endeavours later on.”

The chair receives all disciplinary or ethical complaints first, from skaters, officials, coaches or team leaders participating in any ISU event, and must sit on every three-member panel unless she has a conflict of interest. The hearing process is more inquisitorial than adversarial, and although decisions are made mostly on the papers, there are also in-person hearings. Parties can appeal decisions to the Court of Arbitration for Sport in Lausanne, Switzerland.

Provided the panel has jurisdiction to hear the complaint, disputes can range from alleged breaches of doping rules to more difficult ethical cases, such as those alleging a judge from one country has rewarded their country’s skaters favourably while giving other countries’ competitors lower marks.

While it’s not the panel’s role to assess a judge’s competency (another arm of the ISU deals with training and accreditation), cases of “national bias” are deemed ethical offences, for which the commission must adjudicate.

“It’s a breach of the code of ethics to behave in a way that could bring the sport into disrepute, not to judge fairly and impartially and to manipulate your marks or try to influence someone else to do that. Those national bias cases are really difficult because they are not always that clear,” Petricevic says.

“It takes a lot of mathematical analysis and evidence, which comes through the technical committees and the referees, and the judges that judge the judges – the Officials Assessment Commission. Then we consider the evidence, decide the case, and, if necessary, determine the sanctions.”

Many hats

 Other complicated cases involve blood doping and comparisons with “biological passports”, a high-level athlete’s electronic record that collates and stores, over a period of time, biological markers in their blood. “If the haemoglobin ratios in the skater’s blood change, for example, by taking drugs, then they can take in more oxygen, which could give them an advantage in speed and stamina. So their base haemoglobin levels are screened over a long period of time to see if there are any changes,” she explains. “It can be quite medically complex, with arguments over how altitude, genetics and disease could affect these profiles.

I’m reminded of how many hats Petricevic can wear at any one time: figure skating judge, disciplinary commission chair, barrister and forensic scientist. For 20 years, she worked as a forensic scientist. At the turn of the millennium, she led a lot of the initial research into what was then a new field – the ability to extract, from very small samples left behind on door handles, in shoes, or from footprints, a person’s DNA.

It was ground-breaking work globally which Petricevic continued in France, having earned a senior fellowship scholarship from the Institute of Environmental Science and Research (ESR). Together with a French student, they researched skin-to-skin transfer of DNA.

“For example, imagine someone is attacked and pulled away by an assailant. Can you pick up the assailant’s DNA on their skin? The answer is sometimes; it depends on a whole range of factors. We looked at this as well as saliva transfer, which was an odd project because it involved volunteers planting a kiss on the arm. Then we tried to analyse their DNA. We had to get ethics approval, of course, but there was no shortage of volunteers to assist.”

Different meanings

 Petricevic served as a key Crown witness in the 2001 RSA murders case, for which William Bell was convicted and imprisoned, and the 1996 hammer killing of Tania Furlan. Petricevic also helped find the DNA profile that correlated to a suspect’s profile in the 1987 murder of six-year-old Teresa Cormack.

More than 800 samples had been screened by the time Petricevic came to the tail end of likeliest possibilities. And it had taken 14 years for the technology to have advanced enough to test the offender’s semen sample on a microscope slide.

Petricevic says deciding when the right time was to test the samples, was one of the most difficult aspects of the case. “Of course, it’s not a single person’s decision … But there must be a high likelihood of getting a result because this could be the last opportunity. There wasn’t much sample. When you analyse a sample like that, it is broken down. And then you use most or all of what is left and if that’s the last sample, you want to be jolly sure you’re going to get a result.”

Eventually a profile in one of the last batches returned a match, which was reanalysed for qualityassurance. She remembers the match occurred toward the end of the day, “because we were doing all our other casework. It wasn’t just me, there were technicians working with me as well,” she says. “In fact, they would have been the ones who ran the samples through and then gave me the results, and then I checked all the results. It was a real team effort.”

At the trial of Cormack’s killer, Jules Mikus, Petricevic described the likelihood of obtaining the DNA profiling result they found was at least 60 million times greater if the DNA came from Mikus than if it came from another man chosen at random from the New Zealand population.

It’s a phrasing she always used, “because you have to memorise that because the likelihood ratio, which is the statistic behind a DNA profiling result, is very specific. If you change the words around, it says something quite different…I’m not saying, ‘it’s 60 million times more likely it came from him’ or ‘it’s 60 million times more likely it was him’. It’s neither of those. But what it says is, ‘the likelihood of getting this particular result is X-times greater if it came from him than if it came from someone else in the population’.”

That Petricevic found Mikus isn’t entirely right either. What she found, she says, was a match that correlated to his DNA profile, “at the sites tested. See, the scientist is coming out of me. See the difference between the science and the law? It’s very precise.

The law

 Science and the law are both “extremely analytical”, she says. Scientific research is done because someone is working to discover the way something works or create something new, whereas the law is about looking back at precedents and then developing it in that way. “In law, there’s always that beautiful scope for the grey area. With science, not so much.”

After returning from France in 2004, and having finished her law degree part-time by then, Petricevic left ESR in 2006 and worked as a Crown prosecutor until 2014. Then she spent four years prosecuting health and safety cases for WorkSafe before switching to the defence bar in 2018. She’s also a member of ADLS’s criminal law and health and saftey law committees. Having been an expert witness more than a hundred times in court, giving evidence on drugs analysis and toxicology, crime scenes and bloodstain pattern analysis, and DNA profiling, moving into criminal law was an obvious career move.

“I’ve always been interested in criminal law, the broader tapestry of criminal behaviour, I suppose. Looking at it from the forensics and the crime scenes, then through to prosecution and then the defence bar, you get a broad perspective,” she says.

Her science background proved useful. “At that stage, DNA was still reasonably new so there weren’t that many practitioners who were across it. I certainly had an advantage in understanding it and being able to assimilate it quickly and then pick the holes and know the questions.” Advocating for defendants has been equally rewarding.

“In the lab, you are an independent expert. You would very rarely meet anyone involved with a case other than occasionally the lawyers and police. Even in the prosecution, you don’t have the same interaction with a client. You’re one step removed from the complainant because you’re acting on behalf of the Crown. Whereas on the defence side, you’re really down there working with the defendant.”

Working with people who are depending on you to help them through the criminal justice system is a privilege, she says. It’s also a responsibility. “You see the effects on the family as well, when someone’s going through the court system to their ultimate conclusion – whatever that may be.

Petricevic might be a newcomer to the Bar, but with a career spanning the law, science, and sports, she’s one of its most experienced. Her advice to others contemplating a switch? “If there’s something you really want to do, start setting those goals and then everything will fall into place,” she says. “I really believe that because it’s happened for me so many times.” ■


Subscribe to


The weekly online publication is full of journalistic articles written for those in the legal profession. With interviews, thought pieces, case notes and analysis of current legal events, LawNews is a key source of news and insights for anyone working within or alongside the legal field.

Sign in or
become a Member
to join the discussion.


Submit a Comment

Your email address will not be published. Required fields are marked *

Latest Articles