Expert explains multiple personality disorder defense

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SALT LAKE CITY -- If a murder trial ever takes place in the Ethan Stacy case, it's possible the defense could be based on mental illness issues. For Nathan Sloop, there may be a claim that he suffers from the so-called multiple personality disorder.

Sloop claims to have different personalities, including the dark and dangerous one he refers to by the names "New York" or "Ghost."

What is ... the Utah insanity defense statute?

The statute states: It is a defense to a prosecution under any statute or ordinance that the defendant, as a result of mental illness, lacked the mental state required as an element of the offense charged.

A relative has already raised that alternate personality as a possible explanation for the crime. But are such notions based on real science, or pure Hollywood?

Joanne Woodward won an Oscar playing "The Three Faces of Eve," including mousey Eve White and wild Eve Black. And Sally Field won an Emmy for playing 13 personalities in the movie "Sybil."

So, multiple personalities win acting awards, but can they win court cases?

Dr. David Tomb, a psychiatrist at Valley Mental Health, says, "There have been a number of cases in which that's been the defense. Usually it has not worked."

Tomb says it is a recognized disorder.

"It does occur. It's a real phenomenon. It's not all that common, and it doesn't look as Hollywood would want us to believe," he explains.

He says the personalities are often just fragments, not sharply defined and completely separate, as they are overdramatized in movies.

"Sometimes that fragment or that other personality will be aware of the primary person. Sometimes they won't," Tomb says.

Nathan Sloop attributes his bad behavior to a separate personality. But if one personality blames another, does that get the person off the hook from a legal or moral perspective? Dr. Tomb says that issue often is debated.

He believes it's like hypnosis. A person usually won't do something strongly against their basic beliefs.

"Usually, it's hard for a ‘bad' personality -- if you can label one of the personalities ‘bad' -- to be doing outrageous things that the base personality would not do," Tomb says.

Some psychiatrists don't believe multiple personality disorders really happen at all.

Dr. Tomb says it's increasingly accepted by the profession. But when it's used as a defense, it's a tough sell to doctors and to juries.

E-mail: hollenhorst@ksl.com