Defense attorneys for a former street preacher charged in the abduction of Elizabeth Smart in Utah wrapped up their case Thursday after seven days of testimony from about two dozen witnesses.

The final witness, clinical psychologist Dr. Richart DeMier, told jurors an assessment done four decades ago as part of a Juvenile Court referral found defendant Brian David Mitchell was pre-psychotic at the age of 16.

By the 1990s, he was married with a job and was a leader at his Mormon church when something triggered a change, the psychologist said.

"Within a very short time he abandons his job, is rejected by his family, is rejected by his church, starts wearing robes that he calls 'garments of humility,' stops paying bills and starts living in the woods," said DeMier, who works for the U.S. Bureau of Prisons.

Mitchell, now 57, is charged in U.S. District Court with kidnapping and unlawful transportation of a minor across state lines. If convicted, he could spend the rest of his life in jail.

Defense attorneys don't dispute that Smart was taken from her home at knifepoint on June 5, 2002, and recovered nine months later on March 12, 2003. But they've tried to build an insanity defense, claiming Mitchell is mentally ill and can't be held responsible.

Whether they have proved that will be up to the jury, defense attorney Parker Douglas said after court recessed. "There's a lot to consider," he said.

Prosecutors are expected to present five days of rebuttal testimony before the case is handed over to jurors for deliberations beginning Dec. 10.

Rebuttal testimony could come from Dr. Michael Welner, a New York forensic psychiatrist who was paid more than $500,000 to evaluate Mitchell for prosecutors in 2009.

Welner concluded Mitchell was faking mental illness to avoid prosecution, also known as malingering.

DeMier was ordered by a court to evaluate Mitchell at a prison hospital in 2008 and determine if he was competent to stand trial. DeMier diagnosed Mitchell as a paranoid schizophrenic.

DeMier said he based his diagnosis on Mitchell's specific, grandiose religious delusions after reviewing thousands of pages of court and medical records, other evaluations of Mitchell, and taped interviews of Smart after she was found.

DeMier told jurors he considered the possibility that Mitchell was faking but concluded he didn't exhibit the patterns of inconsistent behavior typically seen in patients who malinger. Most of his patients want to be seen as mentally ill, but Mitchell doesn't, DeMier said.

"I think it's abhorrent to him, the idea that he's mentally ill ... he rejects that," DeMier said.

Accepting a diagnosis of mental illness would also invalidate Mitchell's belief system, the doctors said.

"He would probably consider it greatly offensive to God to abandon his beliefs," DeMier said.

He said Mitchell, who asked to be called by his religious name Immanuel David Isaiah during the evaluation, believes he will rise up to fight and defeat the anti-Christ at the end of the world.

He also believes he has been ordained by God as the "Davidic King" and that he will take multiple wives — perhaps as many as 49, DeMier said.

Mitchell said he had received a special dispensation from the Lord to speak with DeMier but would only cooperate as long as DeMier's mind and heart were open to his message, according to testimony.

Mitchell stopped talking to DeMier after about five hours of interviews.

Smart was 14 when she was kidnapped.

Now, 23, she has testified that she was forced to enter a polygamous marriage with Mitchell, endured near daily rapes, was forced to use drugs and alcohol, and was taken to California against her will.

Mitchell was again removed from court Thursday after spending more than 20 minutes singing Christmas carols. He watched the trial from a holding cell elsewhere in the courthouse.