Find rape killer with victim saliva

If the blue beard lover kisses the woman he attacked sexually, police can analyze the DNA in the victim's saliva to find the culprit.

When a married couple kisses, their mouths receive bacteria, saliva and DNA of the "partner". Regardless of how long the kiss lasts, their DNA will survive in each other's saliva for at least an hour. Thus, women's saliva may contain evidence of the rapist's offense, or adultery behavior of peach blossom gentlemen.

Men's DNA can survive in women's saliva for at least an hour.

Natalia Kamodyova, a researcher from Comenius University in Slovakia and colleagues recruited 12 pairs of men and women who agreed to kiss for at least two minutes. After 5, 10, 30 and 60 minutes since the couples kissed, the team took turns sampling the saliva in the mouths of the women. Because Kamodyova's method only detects Y chromosomes, they can only apply it to identify male DNA in female saliva.

Results showed that men's DNA persisted in women's saliva for at least an hour after the couple kissed.

"We have shown that we can identify the identity of a man who kissed a woman by analyzing a woman's saliva. This method can become useful in investigating activities. With it, the police can identify the culprits among the suspects and eliminate innocent people, " Kamodyova said.

Kamodyova's team will continue to study to see if DNA can last longer than an hour in women's saliva and whether it is feasible to take DNA from the mouths of newly dead women.