Improved Blood Test Helping FBI Get Its Man

The FBI is using a new technique that can separate the innocent from the guilty with a single drop of blood, an FBI chemist said.

The technique, called isoelectric focusing, is a marked improvement over the blood analyses used by the agency’s forensic scientists for the last 15 years, said Bruce Budowle, a research chemist at the FBI Academy at Quantico, Va.

“We can make five to 10 analyses on a single drop of blood and find at least three genetically-determined markers that absolve the innocent and point to the guilty,” Budowle said in a paper delivered at the American Chemical Society.

The three “markers” are variations of enzymes and other proteins found in human blood. Each of the markers is somewhat uncommon, so they can be used singularly or together to help pinpoint a suspect.

“Because of the multiplying effect, each marker dramatically narrows the field of suspects,” he said, pointing out that only one in 600 people has all three markers.

“No one is likely to be convicted by blood evidence alone,” Budowle acknowledged.

However, he said, when a jury is told that the suspect has all three markers, and only one in 600 people has them all, “and he was at the scene of the crime, your case against him is stronger.”