CNN looks back at the heinous kidnapping, the couple charged and how the crime might have been prevented. Don't miss "Taken: The Kidnapping of Elizabeth Smart," at 10 p.m. ET Saturday and at 10:30 p.m. ET Sunday.
(CNN) -- Witnesses recalled Brian David Mitchell as a clean-cut member of the Church of Jesus Christ of Latter-day Saints as the defense case began for the self-described prophet accused of kidnapping Elizabeth Smart.
Mitchell was "persecuted" for his religious zeal, former co-worker Doug Larsen testified, but sang hymns to drown out the crudeness of those around him.
"I heard him in the courtroom once, and he sang about at the same pitch," Larsen told the jury.
Mitchell enters singing as his trial begins each morning in U.S. District Court. On most other days, he chooses obscure hymns. But on Tuesday he switched to a holiday theme, singing Christmas classics such as "Joy to the World," "O Come, All Ye Faithful" and "Silent Night."
The prosecution rested Tuesday, after calling 10 witnesses, including Smart herself.
Smart, who turned 23 earlier this month, spent three days on the stand, describing how she awoke to find a knife blade to her throat and was taken from her bed early on June 5, 2002.
She testified that she was led to a primitive mountainside camp, "sealed" in marriage to her captor, raped and tethered between two trees "like an animal."
Smart testified that she was told she was preordained to be the wife of Mitchell, who also went by the name Immanuel David Isaiah. She said he told her he was to take seven wives, then multiply that number sevenfold. Her role, she said, was to train the others on how to perform their sexual duties.
Smart was 14 when she was snatched from her bed at knifepoint. She was freed by police in Sandy, Utah, on March 12, 2003, as she, Mitchell and Barzee, returned from a winter trip to California.
Barzee was sentenced to up to 15 years in prison earlier this year after pleading guilty to state and federal charges for her role in the abduction.
Attorneys for Mitchell, now 57, are mounting an insanity defense, claiming Mitchell descended into mental illness in the years before abducting Smart. They say he was so impaired by mental illness that he did not know that what he was doing was wrong.
The defense lists two dozen potential witnesses, among them Barzee, Mitchell's father, and a psychologist who testified on Mitchell's behalf at a competency hearing.
Four men took the witness stand for the defense on Tuesday. All said they observed the change in Mitchell as he began to dress in robes and call himself "Immanuel."
Larsen, who befriended Mitchell at work, described him as "utterly sincere" in his religious beliefs and focused on his role as "father, priesthood holder, and husband." After the two lost touch, Larsen began hearing rumors of a robed Mitchell roaming the streets of Salt Lake City.
Larsen told the jury he once spotted his former colleague begging for money, but Mitchell refused to acknowledge him. Larsen grabbed his arm and pushed a $5 bill into his pocket:
"I said 'You gave that guy back there a God Bless You for 50 cents. Will you give me five minutes of your time for $5?'"
Mitchell broke free and walked away, and Larsen called out that he'd pray for him.
"And he looked over his shoulder and said 'And I'll pray for you,' and that's the last words he ever said to me," Larsen testified.
Also on the stand Tuesday were the two sons of Dr. Samuel West, a man interested in medical treatments involving the lymph system, who testified Mitchell worked with their father until his irrational behavior and increasingly odd religious convictions ended the relationship.
Mitchell faces life in prison if he is convicted of kidnapping and transporting a minor across state lines for sexual purposes.