ROCKVILLE, Md. – In an often testy four-hour cross-examination, John Allen Muhammad questioned the mental health and memory of his one-time sniper protege Lee Boyd Malvo and repeatedly referred to him as “son.”

“I would prefer you address me by my name,” Malvo shot back at one point, drawing an apology from the defendant.

But when Muhammad discussed what had been a father-son-like bond between the two, Malvo’s soft voice grew quieter and he hunched down in the witness chair.

Muhammad, defending himself against murder charges in six Maryland killings, tried to counter Malvo’s damaging testimony Tuesday that he sought to spread terror in the Washington region in October 2002. Muhammad often demanded yes-or-no answers and complained when Malvo gave longer replies.

Muhammad, already sentenced to death in a Virginia murder, pointed to Malvo’s first sniper trial in Virginia, where Malvo pleaded guilty by reason of insanity and was sentenced to life in prison.

“Who decided you was insane? … How many doctors said you was insane?” Muhammad asked.

“They said I was indoctrinated,” Malvo responded, referring to his Virginia attorney’s claims that Muhammad brainwashed him and turned him into a killer.

Muhammad didn’t challenge some of the wild schemes Malvo described Tuesday. Malvo testified that Muhammad wanted to shoot six people a day for a month, then use explosives to kill children in schools, on school buses and in children’s hospitals.

Instead of pressing Malvo on those accounts, Muhammad grilled him about minor details of some crime scenes, trying to show Malvo’s memory was flawed. He suggested Malvo had a problem with exaggeration. He repeatedly asked Malvo about guns and how they work, trying to counter Malvo’s claim that Muhammad taught him how to fire the high-powered Bushmaster rifle used in the killings.

Muhammad, 45, began his defense late yesterday afternoon after prosecutors rested their case following nearly three weeks of testimony. His first witness was a woman who was in the parking lot of a shopping center where James Martin was shot October 2, 2002, in Wheaton.

Referring to the influence he once held over Malvo, Muhammad asked him whether the word “indoctrinated” also could include a positive influence. Malvo said yes.

Muhammad recalled a moment when Malvo saved Muhammad’s young son, John Jr., from drowning. “Son, I mean Mr. Malvo, isn’t it true that if the roles were turned, and Lee Boyd Malvo was in that water, that John Allen Muhammad would have got him?” Muhammad asked.

Prosecutors objected and Circuit Judge James Ryan wouldn’t let Malvo answer.

Questioned later by prosecutors, Malvo said Muhammad treated him differently than he treated his own young children.

“Mr. Muhammad did not use any of his children to murder other people,” Malvo said.

Malvo, 21, agreed to plead guilty and be sentenced to life in prison for the six Maryland murders for which Muhammad is being tried. Malvo said Tuesday he wanted to testify to confront Muhammad and give the victims’ families some answers.

Ten people were killed and three wounded in the Washington region during the three-week spree in October 2002.

Malvo said he shot three of the victims, while Muhammad was the triggerman in the rest of the shootings.

Malvo also said Muhammad, who is black, hated America, and believed that “the white man was the devil.” Muhammad noted during his cross-examination that many of his friends, including an ex-girlfriend, are white.

But questioned later by prosecutors, Malvo said he confronted Muhammad about the apparent contradiction, telling him to choose between his girlfriend and Malvo. Muhammad broke off his relationship with the woman.

“How did he make you feel about white people at that time, Mr. Malvo?” a Montgomery County deputy state’s attorney, Katherine Winfree, asked.

“Hate,” he said.