"If we succeed in developing a sure-fire method to determine the age of a trace, the police will have a tool to determine whether a fingerprint or other trace is relevant to the investigation. It will be a ground-breaking method, as there is currently no alternative option"
Some criminal cases have a crime scene that is teeming with fingerprints and other biological traces. An important part of the work of the police is to find out which traces are relevant to the case - and this discovery can help to convict or acquit the people involved.
Assistant Professor Kirstine Lykke Nielsen, born in 1983, is one of the researchers behind the TraceAge project, which focuses on finding biomarkers for determining the age of bloodstains and fingerprints. The markers reveal when a biological trace was made and the research project has the potential to develop tools that can play a significant role in police investigations.
"If we succeed in developing a sure-fire method to determine the age of a trace, the police will have a tool to determine whether a fingerprint or other trace is relevant to the investigation. It will be a ground-breaking method, as there is currently no alternative option," she explains.
Metabolomics is the study of changes in the small molecules that are formed or metabolised by different cellular processes, also known as the metabolism. The team behind TraceAge uses tools from untargeted metabolomics to identify biomarkers in blood and fingerprints such as those that can be found at a crime scene. No metabolic processes occur when blood is broken down on a non-biological surface, but the researchers use the tools from metabolomics to identify the relevant biomarkers and their degradation patterns.
Kirstine Lykke Nielsen uses liquid chromatography combined with mass spectrometry (LC-MS), enabling her to measure many molecules in blood, urine, tissues or cells at the same time.
In order to spot changes, she carries out a comparison with a control group using statistics and multivariate data analysis, and this enables her to identify specific biomarkers out of what are often several thousand variables. Metabolomics is very explorative and can be used in many contexts to examine differences in the metabolism between two or more groups of people or samples, e.g. in connection with illness, nutrition or toxicology. The changes that are measured can subsequently be further examined.
Kirstine Lykke Nielsen was introduced to metabolomics during her PhD studies at the Department of Animal Science at Aarhus University. The PhD project provided better insight into the metabolism of fast and slowly digestible carbohydrates, including the acute effect of dietary fibres. Kirstine Lykke Nielsen conducted experiments involving both pigs and humans.
"We took blood samples before and after meals and after a longer period with a specific diet, and the results helped to underline the effects of the different diets. It also provided valuable insight into the differences between the digestion systems of pigs and humans. This is knowledge I take with me in my further research into metabolomics," she says.
She is also involved in studies with data from forensic screenings, which are e.g. carried out to determine whether a person has driven a car under the influence of drugs. This data can also be used to detect metabolites and endogenous changes caused by drug intake, and can therefore be used to examine the biological and toxicological effects of different substances.
In 2019, Kirstine Lykke Nielsen received DKK 8.6 million from the Innovation Fund Denmark towards the TraceAge research project on the age of biological traces.