What kind of forensic investigators analyzes hair

Forensics: How forensic medicine tries to extract more information from hair

Can you read your age and gender, diet and lifestyle precisely from a hair sample? There is still some way to go before then, but US researchers are taking the first steps. With isotope analyzes, forensic scientists want to coax this information out of hair in the future and thus also advance forensic medicine. You hope a lot from analyzing hair.

The method on hair has advantages over DNA analysis because it says more about the lifestyle of the person, reported Glen Jackson's team at a meeting of the American Chemical Society in San Francisco. "You could have genetically identical twins, and if one is overweight and the other is slim, our method could possibly tell that difference in your hair." However, in addition to Jackson and German experts, there are still many unanswered questions.

So far, researchers have been able to find this out with the help of hair

The chemists headed by Jackson from West Virginia University, according to their information, succeeded in correctly determining the hair owner's body mass index from the hair of 20 women with an 80 percent probability. The hit rate in another attempt to determine the correct gender from among 20 hair samples from men and women was 90 percent, according to researchers.

But how does this hair analysis technique work? The focus is on elements that are found in the hair component keratin, such as carbon and nitrogen. They are available in different variants - experts speak of isotopes. Depending on the diet and lifestyle, the isotopes of an element have a certain ratio to one another. Several such isotope ratios can be used to generate a kind of fingerprint that differs from person to person - just not with the help of fingers, but with hair.

German forensic scientists doubt hair analysis by US researchers

Forensics experts from Heidelberg University say that the US chemists' approach is "quite charming", but they remain skeptical in view of the low number of cases, few details and the lack of comparables with significant biomarkers. "Previous experience with isotope analyzes in forensic medicine as well as with toxicological hair analyzes give rise to certain doubts that it will be possible in the foreseeable future to be able to make statements from hair analyzes with such accuracy as would be required in criminal law," said Kathrin Yen from the institute convincing for forensic medicine and traffic medicine.

What other approaches are there so far? Because the DNA in hair is fragile and, depending on the weather, can quickly become brittle, researchers are trying to classify hair on the basis of prominent protein sites. Because proteins are much more robust than DNA. Another idea comes from molecular biology. Marc Bartel (University of Heidelberg) reports that attempts are being made there to obtain information on lifestyle habits from specific changes in the DNA strand (DNA methylation).

The isotope analysis of hair is not only a research topic in the USA. Forensic doctors at the LMU Munich have been researching for a long time using isotope examinations of hair to determine the geographical origin of the deceased. In Germany, hair analyzes are currently being carried out in forensic toxicology to detect alcohol, drugs or medication. Consumption months ago can also be proven in this way. dpa / sh