Salt Lake City, Utah (CNN) -- Brian David Mitchell told police Elizabeth Smart was "converted by the priority of God" and willingly stayed with him after she vanished from her bedroom in June 2002.
"The Lord God delivered her," he told police.
Jurors watched police grill him on a two-hour video played Monday at Mitchell's federal kidnapping trial. On the video, Mitchell offered religious responses to questions posed by an FBI agent and a police detective from Salt Lake City, Utah.
Mitchell, his wife, Wanda Barzee, and Smart were taken into custody on March 12, 2003, as they left a Wal-Mart store in suburban Sandy, Utah. They were hitchhiking back from a winter trip to California and headed to a remote mountain campsite when passersby recognized Mitchell and called police.
Mitchell, 57, is charged with kidnapping and transporting a minor across state lines for sex. He could face life in prison if convicted. His lawyers are raising an insanity defense.
Smart, now 23, was composed and certain as she recounted her ordeal during three days of riveting testimony last week.
She said Mitchell snatched her from her bed at knifepoint and led her to a makeshift mountain camp, where he chained and degraded her as he repeatedly raped her.
As the trial entered its second week, testimony focused on the final days of Smart's ordeal.
At times, Mitchell's voice was nearly inaudible on the tape of his police interrogation.
"Not to be too obvious about it, but we've been looking for Elizabeth Smart for some nine months, and she's with you," an unidentified investigator says as the taped interview begins. "And we'd like to know how that came about."
Mitchell, who responds to the name Immanuel, tells police God had led Smart to him: "She was converted by the spirit of God. If you read the book you will understand."
Asked whether his name in the secular world is Brian David Mitchell, Mitchell responds that the question is of no relevance: "I've forsaken the world. It is immaterial to ask me such a question."
He told investigators that the Lord told him Smart was 18. She was 14 when, she testified, Mitchell abducted her at knifepoint from the bed she shared with her sister and led her to a campsite high in the mountains.
Asked if he had sexual intercourse with Smart, Mitchell becomes evasive, saying the question is "too personal." Asked if he took her from her home, he responds, "The Lord God delivered her."
Investigators repeatedly tried to steer him back to the subject of Smart, and he repeatedly deflected their questions with religious speeches.
"So far I have no idea what you're talking about," said one investigator. "For the past nine months, this family has gone through hell."
He tells Mitchell hundreds of law enforcement officers spent hours looking for Smart and the family had thought she was dead.
"They expected to find a corpse," he said.
Mitchell continues with his religious talk, but never directly responds to investigators' questions.
The investigator takes a direct tack: "We've been talking to this girl and she's been saying some really terrible things about you, and I'm going to ask you some direct questions."
Investigator: "Did you take that girl from her house? Yes, or no?"
Mitchell: "I'm not going to answer that question."
Investigator: "We want to be able to go to Elizabeth's family. ... We want to be able to have an explanation for them. You have to feel sorry for them."
Mitchell: "I have great compassion and love for them, because they are the parents of my ... " -- voice trails off.
Investigator: "Oh, [expletive] You took her out of her house!"
The investigator accuses Mitchell of laying the groundwork for an insanity defense, and accuses him of being on a "pretty big power trip."
"I'm just obedient to what God told me to do," Mitchell responds.
"You understand these charges could potentially keep you behind bars for the rest of your life?" the investigator asks.
Mitchell responds, "It mattereth not ... prison or death, it mattereth not."
Mitchell accuses police of trying to get him to say something false, and an investigator notes, "This is getting a little too intense for you, isn't it? ... You keep retreating into your spiel and your diatribe."
"The core of the problem is you, and you are not a prophet and you are not a servant of Jesus Christ. You are Brian David Mitchell," the frustrated investigator states, "and you have done something awful."
The investigator raises his voice:
"If heaven's filled with people like you, I'd be more comfortable in hell! ... You are Brian David Mitchell, and you are a child molester. A criminal. You are a hypocrite and a fraud."
Mitchell repeatedly denies he raped Smart.
"I have only done what the Lord God almighty commanded me to do," he says. "You're asking me to speak about things which are sacred and holy and which I cannot talk about."
"I thought she was 18. And she willingly chose to be sealed," Mitchell says.
Mitchell begins to sing in the interrogation room, as he has at every court hearing since December 2004. An investigator joins him for a while.
As they begin to speak with him again, Mitchell screams, "Get thee behind me Satan!" several times.
"You are not a servant of the Lord. You have harmed a child," says an investigator once Mitchell quiets. "You need to evaluate your life."
"You don't have any power here. You don't speak for Jesus Christ," Mitchell is told. "Your name is Brian Mitchell, and you're attracted to young girls, and you're just a loser. ... You're not going down as a servant of God. You're going down as a child rapist. You're going down as the lowest of the low."
As Mitchell sits silently with his eyes closed, the investigator says: "I hate to tell you this, Brian, but the Rapture has not happened. You are still in this room. You cannot escape."
The investigators taunt him about Smart:
"She gave you up."
"She thinks that you are a child rapist."
"She finds you rather smelly, and disgusting."
Later, FBI agent George Dougherty interviewed Mitchell for several days, finally winning a major concession. "Did you then consummate your marriage to make it a true union?" he said he asked. "And he said 'Yes.'"
CNN's Ann O'Neill and In Session's Jean Casarez contributed to this story.