Dr. Harald Schneider from the Criminal Investigation Institute (KTI) of the Hessian Criminal Police Office (HLKA) is head of the Biology, DNA Analysis, Textile Science department. After studying molecular biology and completing his doctorate at the Institute for Molecular Biology and Tumor Research in Marburg, he was commissioned to set up the DNA department of the HLKA in 1991. Since then, under his leadership, more than 750 homicides and around 5000 sex crimes have been solved using genetic fingerprinting alone. Over the last 20 years, his group has specialized in the processing of unsolved capital crimes - so-called "cold cases" - some of which date back decades, with a success rate that is unique in Germany.
The task of securing evidence
The task of the KTI is to examine mainly material evidence from crime scenes in order to shed light on the course of events in a crime or to provide information about the perpetrators. This material evidence is important both for police investigations and for providing evidence in court. In the Biology department, fiber analyses are carried out in the Textile Science department, while the DNA Analysis department focuses on the analysis of DNA material. Harald Schneider makes it clear that the examination of fiber traces, DNA traces (blood, skin abrasion) and fingerprints, for example from a murder weapon, must be carried out in the correct order: "Fiber traces, for example, are the most volatile, which is why the weapon must be examined first for those traces."
A career in criminal biology
Schneider talks enthusiastically about his work, which consists of forensics, laboratory work, court appearances and a lot of office work. He explains to the audience, mainly bioscientists, that a doctorate is usually desirable for a career as a criminal biologist and that an affinity for bioinformatics and experience/willingness to work in laboratory analysis, office work and press and public relations is required.
Areas of application of genetic fingerprinting
Another topic of the lecture was the rapid development of DNA analysis and the use of genetic fingerprinting in forensics and crime investigation. Genetic fingerprints are used to reconstruct crimes, to identify links between crimes (series of murders at different crime scenes), but especially to exonerate suspects, as well as to solve unsolved old cases and for parentage investigations.
Limits, risks and possibilities of DNA traces
But Harald Schneider can also point out some of the limitations of DNA traces. For example, it is currently not possible to determine their age. "What we need are biomarkers that allow us to make statements about the age of a DNA trace based on a half-life," explains the criminal biologist. "And data protection in Germany also makes it difficult for us: we are not allowed to use biogeographical origin and appearance characteristics that emerge from the genetic fingerprint, which of course severely limits the resolution of some cases." Another problem Schneider mentions is background noise, which increases significantly with increasing specialization. On the one hand, a large number of samples and ever smaller DNA traces can be examined today, so that every culprit actually leaves traces at the crime scene. However, DNA traces are easily transportable and even if the DNA found at the crime scene can be assigned to a person in the database, it does not necessarily mean that it is relevant to the crime, because every crime scene is teeming with countless DNA traces that may have arrived at the scene in a variety of ways.