A bite can bait a burglar

Police say thieves often cannot resist tucking into a snack after breaking into a home, and traces of saliva on the food remains can yield a telltale signature of the criminal’s DNA.

  

A handful of hungry crooks have been caught and jailed this way over the past decade, a phenomenon that has prompted curious scientists to wonder which foods may yield the best saliva sample.

  

Forensic researchers Heather Zarsky and Ismail Sebetan of the National University in La Jolla, California, organised a dinner party for 13 people, the British weekly New Scientist reports.

 

The menu

  

On the menu were pizza, corn on the cob, chicken wings, ribs, chocolates, cheese, apples and carrots.

  

“The message is that police investigators should [systematically] collect food at the scene [of a crime] and try it for DNA” Heather Zarsky, forensic researcher

Guests were told to take a couple of bites of whatever took their fancy and leave the remains behind.

  

Zarsky and Sebetan collected the half-eaten food and used swabs to try to recover human DNA from the bitten areas.

  

Complete profiles were recovered from 43% of the swabs, and partial profiles from 33%. The remaining 24% of the swabs had too little DNA to yield even a partial profile.

  

Cheese, carrots, apples and pizza returned the highest scores, while the chocolates were almost useless, possibly because they were bite-sized chunks and little saliva was left behind.

  

“The message is that police investigators should [systematically] collect food at the scene [of a crime] and try it for DNA,” Zarsky told New Scientist.

  

The report appears in next Saturday’s issue.