Guilt phase of Boston Marathon bombing trial winding down; penalty phase is next

BOSTON — An admission by Dzhokhar Tsarnaev that he bombed the Boston Marathon has vastly accelerated the pace of his federal death penalty trial. While the trial was originally expected to last three to four months, it could be over in about half that time. Prosecutors could rest their case in the guilt phase as early as next week. With a relatively brief case expected from the defense, the trial could soon move to the penalty phase, when the same jury will decide whether Tsarnaev is sentenced to death or spends the rest of his life in prison.

Here are a few things to know as the trial moves forward:

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THE CHARGES

Tsarnaev faces 30 federal charges for conspiring and carrying out twin bombings with his older brother, Tamerlan, who was killed three days later during a gunbattle with police. Three people were killed and more than 260 were injured when two pressure-cooker bombs exploded within seconds of each other near the marathon finish line on April 15, 2013. Tsarnaev is also charged in the killing of a Massachusetts Institute of Technology police officer and a violent confrontation with police that nearly killed a transit police officer. During opening statements, Tsarnaev's attorney, Judy Clarke, bluntly told the jury, "It was him," admitting her client participated in the bombings. But Clarke said Tamerlan, 26, was the mastermind who enlisted the then-19-year-old Dzhokhar to participate. Prosecutors say Dzhokhar was an active and willing participant who knowingly placed one of the bombs near a group of children, killing 8-year-old Martin Richard.

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THE GUILT PHASE

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WHAT'S NEXT

Prosecutors are expected to wrap up their case in the guilt phase within a week. The witness list remains sealed from public view, so it's difficult to know exactly who the remaining prosecution witnesses are. Based on an outline of the case given by Assistant U.S. Attorney William Weinreb in his opening statement, it appears that prosecutors will call a worker at a firing range in Manchester, New Hampshire, where both brothers practiced shooting less than a month before the marathon bombings. Weinreb said their shooting practice shows that both planned to use a Ruger handgun that ended up being used to kill MIT police Officer Sean Collier three days after the bombings. Prosecutors also may call one of two college friends convicted of impeding the investigation by throwing away Dzhokhar's backpack after the bombing. The backpack contained fireworks that had been emptied of their explosive powder. On Monday, an FBI computer expert is expected to be cross-examined by defense attorneys about extremist materials found on Dzhokhar's laptop and other devices.

The defense case in the guilt phase is more difficult to predict, but Tsarnaev's lawyers may try to rebut testimony that appeared to show he was an active participant in Collier's shooting. During opening statements, Tsarnaev's lawyer admitted much of the conduct alleged by prosecutors but said Tamerlan was the one who shot Collier, not Dzhokhar.

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