james cavanaugh was an expert for the hinkly trial and then for dougan.their brain is abnormal. >> by expansion, we were trying to take that same step with the psychopath but let's face it, there is a big difference between how he public feels about a mentally retarded individual or a child who granted does a horrible thing but is still a kid in terms of applying the death sentence. >> reporter: while the research is gaining traction with some scientists, it is still very new. >> imaging is a helpful tool in the context of trying to understand what brain regions might be implicated in someone committing a horrific crime. to take it a step further and have it be a definitive piece of evidence in the court system, i think we're just many, many years away from that. >> reporter: in the meantime, it could help develop a therapy or medication. the traits of a psychopath are not limited to criminals. they can even be found in ceos. the general population, 1% of men are psychopaths. the rate is much lower for women. what may separate murderer from millionaire is