DNA is the prosecution’s most important piece of evidence. A sure proof, they say. The defendant’s DNA was found on Birgitte’s tights. But he believes he has never met her. The defenders believe his DNA may have come via another person. Or an object. It may even have arrived via air. For four days, experts will talk about the evidence they have found. But is it strong enough? We may get an answer to that in the courtroom this week. An old DNA can be of a poorer quality if it has been stored incorrectly, says DNA expert Solveig Jacobsen. Section leader for forensic genetics in criminal cases at Oslo University Hospital, Solveig Jacobsen. Photo: Oslo University Hospital She is section leader for forensic genetics in criminal cases at Oslo University Hospital (OUS). – It also depends on how much biological material there was originally, says Jacobsen. She makes a general statement about DNA. Many were at the scene. In court, a number of police officers have testified. Police officers who were at the scene after Birgitte Tengs was found murdered on 6 May 1995. Crime scene technicians. People from Kripos. A doctor. Everyone has had to explain what they did in court. Were they careless? Did they consider securing the crime scene? Contamination of tracks? Some have said they didn’t use gloves. Others have said they walked and stomped around the corpse. Several say they don’t remember. Some remember wrongly. The methods for securing a crime scene were quite different in 1995 than today. It is here, among other things, that the defendant’s defenders believe that the evidence may have been tainted. – They did not think about securing the crime scene at all, says defender Stian Kristensen. Birgitte Tengs was killed 27 years ago. A 52-year-old man has been charged with the murder. His DNA is thus found on her pantyhose. Evidence that was secured in 2002. At that time, the police were unable to find the 52-year-old. The sample has now been analyzed using new technology. – We believe this is certain evidence, says prosecutor Thale Thomseth. Four days have been set aside for DNA in court. The prosecution has always been aware that this is their most important piece of evidence. – Yes, this is the main evidence in the case, she says. Where were the pantyhose? A photo of Birgitte Teng’s tights has been shown in court a number of times. As important evidence. DNA from the defendant was found on Birgitte Teng’s tights. DNA from the defendant was secured on a clipping of the pantyhose. The cutout was placed on a glass. And frozen. But this did not happen until October 1996. The DNA expert believes that the quality of a DNA can be lost over time. – The quality can be lost because DNA that is exposed to light and moisture will break down, says Jacobsen at OUS. In court, Thomseth has said that there may be contamination in the period between the murder on 6 May 1995 and October 1996. The tights have been on quite a journey. After the murder, the pantyhose were first transported to the Gades Institute in Bergen. It was then taken back to dry at the police chamber in Haugesund. It was then sent to Kripos in Oslo for investigation. – It is during that period that there can be talk of contamination. The risk of contamination is significantly less after being stored on glass, says prosecutor Thomseth. DNA material can be of poorer quality if it is stored incorrectly. Illustration: Lise Åserud / NTB Casting doubts about DNA Defense attorney Stian Kristensen has constantly cast doubt on the prosecution’s DNA evidence. He believes it is scary to rely solely on DNA findings. – We know so much more about DNA today than a few years ago. We can deposit DNA in air and in dust. And we lose skin cells all the way, says Kristensen. Stian Kristensen defends the 52-year-old defendant in Haugaland and Sunnhordland District Court. Photo: Øystein Otterdal / news A DNA discovery should only be one of several pieces of evidence in a criminal case, according to experts at Oslo University Hospital (OUS). “It should rarely stand alone as conclusive evidence”, writes OUS on its website. – I think several DNA technicians will agree with us when we say that DNA in itself is dangerous to emphasize too much, says the defender. Defense attorney John Christian Elden has also questioned early in the trial how strong the DNA evidence is. More experts in court Several DNA experts will testify in court over four days. They are brought in from Austria, the Netherlands and England. The prosecution wants the court to be confident about the decision they will make. Acting state prosecutor Thale Thomseth. Photo: Øystein Otterdal / news – Many analyzes have been done over the years. Analyzes have been carried out using different methodologies. It is natural that those who carried out the analyzes answer for the work they have done, says Thale Thomseth. The new DNA technology is more sensitive. You need less biological material to analyze traces. But this also requires a certain control. Among other things, on who has taken part in sampling. But also: – Where the sampling has taken place, how the samples have been stored and that you have control over all the steps in the analysis process, says Jacobsen at OUS. Aware of challenges Thomseth is aware of these challenges. The Institute of Forensic Medicine (now OUS) has had several objections in relation to old material. Among other things in relation to pollution. – We already documented that in the introduction. We will of course ask the experts questions about these assessments, says Thomseth. She points out that their DNA evidence is taken from an extract. And that this has been frozen. – Then the experts must be asked if there is any difference for contamination on that point. The 52-year-old defendant denies criminal guilt. He says he has not met Birgitte Tengs. And he has no idea how his DNA ended up on the pantyhose. – No, he has no explanation for that, says Kristensen. Birgitte Tengs was found murdered on 6 May 1995. A 52-year-old man from Karmøy is now charged in the Tengs case, and the trial began on Monday 7 November 2022.
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This week the battle for the DNA evidence is in the courtroom – news Rogaland – Local news, TV and radio
