A year ago, we reported unfavorably on brain fingerprinting, a new technology trying to make its way into the criminal justice system. It's in the news again as its foremost proponent argues it shows a man about to be executed may be innocent:

The technique, called "brain fingerprinting", has already been tested by the FBI and has now become part of the key evidence to overturn the murder conviction of Jimmy Ray Slaughter who is facing execution in Oklahoma.

Brain Fingerprinting, developed by Dr Larry Farwell, chief scientist and founder of Brain Fingerprinting Laboratories, is a method of reading the brain's involuntary electrical activity in response to a subject being shown certain images relating to a crime.....it simply detects scientifically if that information is stored in the brain," says Dr Farwell.

"It doesn't depend upon the subjective interpretation of the person conducting the test. The computer monitors the information and comes up with information present or information absent." .... brain fingerprinting doesn't have anything to do with the emotions, whether a person is sweating or not; it simply detects scientifically if that information is stored in the brain

Dr. Farwell tested Jimmy Ray Slaughter a few days ago in the Oklahoma prison where he awaits execution next week: