CHESAPEAKE, Va. (AP) — Sniper suspect Lee Boyd Malvo "displayed a pathological loyalty" to John Allen Muhammad and was so brainwashed by him that he was legally insane during last year's killing spree, a defense psychiatrist testified Wednesday.

Diane Schetky, who twice interviewed Malvo in jail, said Malvo was unable to distinguish right from wrong when he and Muhammad killed 10 people during a three-week shooting spree in the Washington, D.C., area.

An inability to distinguish right from wrong is the legal standard for insanity in Virginia.

Schetky was the second defense witness to diagnose Malvo with a dissociative disorder, a mental illness that involves a distorted view of reality.

Malvo "displayed a pathological loyalty to Muhammad" and confessed to being the triggerman in the killings when police suggested that the shooter would be the one who took the rap for the crimes, she said.

Malvo, 18, has since recanted his confession and said Muhammad was the triggerman in nearly all of the shootings.

Defense attorneys said another expert, Neil Blumberg, also will testify that Malvo was insane.

As Malvo trained for the sniper spree, Muhammad taught him that emotions were the enemy and should never be allowed to interfere with his paramilitary mission, Schetky said Tuesday.

Muhammad told Malvo that "if his conscience was bothering him, he should lock it up in a box and throw away the key," she said.

Schetky testified Tuesday that Malvo latched on to Muhammad as a father figure when Muhammad cared for him on Antigua in 2000. After Malvo went to Bellingham, Wash., in 2001 to live with Muhammad, he trained Malvo in fitness and firearms and dissuaded Malvo from believing that killing was "absolutely wrong" by using military analogies and religious language, Schetky said.

Schetky also said Muhammad convinced Malvo that "right and wrong" are artificial constructions that have no real meaning.

Prosecutors argued Tuesday that Malvo was a willing participant and challenged the testimony of defense psychologist Dewey Cornell, who also said Malvo had a dissociative disorder and was brainwashed by Muhammad.

Prosecutor Robert F. Horan Jr. noted Malvo ran away twice from his mother Una James -- in late October 2001 and in January 2002 -- and chose to be with Muhammad.

Horan also said Malvo and Muhammad had lived together in the United States for only about 10 weeks before Malvo committed his first killing -- the Feb. 16, 2002, slaying of Keenya Cook in Tacoma, Wash. Malvo has admitted walking up to Cook's house and shooting her in the face at point-blank range.

"By Feb. 16 he goes out and shoots a woman he doesn't even know in the face and kills her," Horan said in cross-examining Cornell. "And it is your testimony he did this because he was indoctrinated by Muhammad?"

Cornell said Malvo's motivation for the Cook killing was to please Muhammad and that it served as Malvo's first test in doing Muhammad's bidding.

Malvo's attorneys are presenting an insanity defense to capital murder charges in the death of Linda Franklin, who was shot in the head on Oct. 14, 2002, as she and her husband loaded packages into their car. Ten people were killed and three were wounded in the spree shootings.

Prosecutors are expected to put on their own mental-health expert, who has been meeting with Malvo since before the trial started Nov. 10.

Muhammad has already been convicted of capital murder for his role in the killings, and a jury recommended a death sentence.