23 November 2010 Last updated at 17:10Test tells age from blood drops
Scientists have developed a technique to estimate the age of a suspect from blood left at a crime scene.
Predicting human "phenotypes" - a person's outward traits such as hair colour or eye colour - from DNA information is a newly emerging field in forensics.
But only a few phenotypic traits can currently be identified from DNA information with enough accuracy to have practical applications.
Lead author Manfred Kayser of the Erasmus MC University Medical Center Rotterdam said his test currently had the highest accuracy of any designed to estimate a "phenotypic" human trait from DNA information.
"Conventional DNA profiling applied in forensics can only identify persons already known to the investigating bodies," Dr Kayser said.
"Hence, every forensic lab is confronted with cases where the DNA profile obtained from the evidence material does not match that of any known suspect tested, nor anybody in the criminal DNA database.
"In such cases, it is expected that appearance information estimated from evidence material will help in finding unknown persons."