Juries hearing the two Washington-area sniper (searchcases have seen many of the same graphic photos of victims, forensic evidence and eyewitness descriptions. But the image of the defendants is dramatically different.

During a week of prosecution evidence, jurors in the Lee Boyd Malvo (searchcase heard more than three hours of tapes from police interviews in which Malvo, 18, confesses to pulling the trigger in all the shootings, brags about his targeting prowess and explains the sniper plan by weaving together the philosophical, logistical and nonsensical.

On the other hand, convicted sniper John Allen Muhammad's (searchjury, which was to resume sentencing deliberations Monday, has no confession, no testimony from Muhammad and no mental health information as it decides whether he should be allowed to live or be executed.

While Muhammad's trial wraps up and Malvo's enters the defense phase, perhaps the biggest difference is that one trial will try to answer the question of why, and the other won't, said Steven D. Benjamin, a Richmond defense attorney experienced in capital murder cases.

"At the end of the Muhammad trial, we will have no better idea of why this happened than we did at the beginning," Benjamin said. "But Malvo's trial has promised to explain what everyone wants to know: who could do something like this and how a child can be turned into a killing machine."

In the tape played for Malvo's jury on Friday, he at times sounds childlike and vulnerable, as when he asks police about the whereabouts of his "father," 42-year-old Muhammad, and if he may have some raisins.

At other times he sounds maniacal and savvy, as when he imitates a lawn-mower noise while describing the deadly shooting of a landscaper, and later chides detectives for asking him a "leading question."

And he is sometimes friendly, insisting he is a "good guy," and suggesting one detective go on a weeklong "grape fast" to cleanse her system — but not say she got the idea from "the sniper."

Prosecutors contend Malvo knew exactly what he was doing during the spree, while defense lawyers argue he was brainwashed by Muhammad and legally insane at the time of the shootings. If convicted, he could be executed.

What Muhammad's jury personally knows of him is mostly limited to two days in which he represented himself and home videos of him playing with his children. Muhammad has denied involvement in the crimes.

Before the trial began, Muhammad refused to meet with the state's mental health evaluators, a move that barred his defense lawyers from putting on their psychological evidence. He also refused to talk to investigators, a situation Malvo anticipated.

"He told us, 'You won't get anything from him,"' June Boyle, the Fairfax County detective who interrogated Malvo, testified Friday.

But Malvo told detectives, "I'll tell you what I can say," Boyle recalled, and went on to talk for hours, though he refused to answer some questions.

He told police the shootings were motivated by greed and would have continued until the government paid them off or until they were captured.

He also said he expected both Muhammad and himself to be executed.

"That's the consequence of failure — death," he told FBI Agent Brad Garrett on the tape.

The pair is accused of killing 10 people and wounding three in the Washington area last year. Malvo is charged with killing Linda Franklin at a Home Depot store in Fairfax County, but to get the death penalty prosecutors must prove the shooting was one of multiple killings or part of a plan to terrorize the area.

A forensic expert testifying last week against Malvo linked bullet fragments from 11 of the shootings to the semiautomatic rifle found in Muhammad's car.

Malvo's attorneys argue that he was indoctrinated and should be found innocent by reason of insanity. Malvo's references to the spree as a carefully planned "battle" show that Muhammad had transformed him into a "child soldier," they say.

Malvo's defense team expects to put up to nine mental health experts and more than 60 witnesses on the stand.