This is a real technology being tested by the FBI. It could become part of the key evidence to overthrow the murder conviction of Jimmy Ray Slaughter, who is facing the death penalty in Oklahoma for assault and murder. It works by picking up the P300 electrical wave emitted by the brain when the subject is shown images relating to a crime. Its strength is that the P300 wave is involuntary - the suspect can’t affect the outcome. It is said to be much more accurate than the polygraph.