Suspect’s alibi easier to verify: The first biological tests to link suspects to time of crime

10 May 2010

It is now, for the first time, possible to ‘read’ at what time of the day biological material , such as blood or saliva, collected at a crime scene was deposited there. This could be an important new tool in criminal investigation as the suspect’s alibi can be verified. Erasmus MC researchers published their findings on the biological tests research online in the journal International Journal of Legal Medicine.

Biological material found at a crime scene is frequently used to identify people using their DNA profile.
A suspect can, however, deny that he/she was at the crime scene at the time of the crime. In his or her defense, he or she could argue, for example, that the material ended up at the crime scene before or after the crime. The research carried out by the Forensic Molecular Biology department of Erasmus MC makes it possible to determine whether this defense is justified.

Prof. Manfred Kayser, head of the Forensic Molecular Biology department (FMB) says: “Our research was based on the natural presence of the hormones melatonin and cortisol in the blood and saliva. During the night there is an increased concentration of melatonin which decreases in the course of the day. The hormone cortisol, on the other hand, has the highest concentration early in the morning, shortly after waking up, and decreases in the course of the day. We found that these hormones could still be shown in very small amounts of blood and saliva. Besides, we demonstrated that the determination of the concentration of the hormones is reliable enough to indicate at what time of the day the biological material was left at the location in question.”

Erasmus MC (FMB) is consortium partner of FGCN.

Read the EMC Press Release »

See also:

Estimating trace deposition time with circadian biomarkers: a prospective and versatile tool for crime scene reconstruction »