Now it may be impossible for even the best liars to conceal their crimes.
The latest technology in forensic science uses details known only to investigators and the criminal to prove a suspect's guilt or innocence. Developed by Harvard-trained Lawrence Farwell, brain fingerprinting uses brainwaves to measure what Farwell calls the "a-ha" of recognition.
Traditional lie detectors rely on reading emotional reactions such as sweating or heart rate as a suspect is asked questions. The problem is that well-practiced liars can control these reactions before the polygraph has a chance to detect them.
That's not a possibility in a brain fingerprint test, says Farwell, chief scientist and founder of the Seattle, Washington-based Brain Fingerprinting Laboratories.
Identifying ‘A-ha’ in the Brain
During the test, the suspect wears a headband equipped with sensors to measure activity in response to recognition of a word or image relating to the crime in question. When the brain recognizes a word or picture, it releases an involuntary wave that Farwell calls a P 300/MERMER (memory and encoding related multifaceted electroencephalographic response). That's used to determine whether suspects were ever at the scene of the crime.
"People remember the very major events in their life, even a serial killer," says Farwell. "That tends to have a very solid record in the brain."
The technology may sound like science fiction, but it has been tested by the FBI and used as evidence in U.S. courts.
According to Farwell and his brain wave results, accused killer Terry Harrington didn't have the details of the 1978 murder he was convicted of stored in his brain. An Iowa judge allowed the new technology into evidence in Herrington's appeal in 2003 — and now he's a free man.
In Missouri, J.B. Grinder confessed and was sentenced to life in 1998 after Farwell's test revealed he did have special knowledge of the 1984 rape-murder of which he was accused.
Now Farwell's technology could exonerate Jimmy Ray Slaughter, a convict on Oklahoma's death row for the murder of his ex-girlfriend and their infant daughter.
Farwell tested Slaughter on details Slaughter claimed he didn't know. When Farwell questioned Slaughter on the location of the bodies at the murder scene and the position of the woman's body on the floor, there was no brain wave of recognition.
The Supreme Court is due to issue a verdict soon on Slaughter's appeal.
Farwell adds that brain fingerprinting could also be used to address the controversial issue of repressed memories of sexual abuse by testing those accused of the abuse.
Acceptance Too Swift?
This isn't the first time investigators have turned to advanced technology to gauge a person's innocence. Researchers have experimented with other computerized brain scans that reveal the amount of blood flow to different sections of the brain. Early tests suggest people use more sections of their brain when they lie than when they tell the truth and this is evident in increased blood flow throughout the brain.
Other law enforcement agencies have used a device that measures changes in the voice. Computer voice stress analyzers are designed to detect lies by monitoring voice frequencies. However, there is a movement in the United States to ban the use of these devices, since there are concerns the analyzers are inaccurate and flawed.
Some argue that acceptance of brain fingerprinting technology has also moved too fast and needs to be refined and tested more before it's used to convict or exonerate suspects.
"There's a lot of value in looking at brain wave activity, but there's also a lot of hype," Frank Horvath, a professor of criminology at Michigan State University told the Seattle Times.
The National Academy of Sciences recently issued a brief assessment of the technology, saying it showed promise, but still needs more study.
Farwell contends plenty of studies have already been done. He invented the test more than 15 years ago and then conducted research with the FBI, the CIA and the U.S. Navy.
"The government spent over $1 million on brain fingerprinting," he says. "We showed not only in the laboratory but in over 100 actual real-life situations that the technology was effective."