BOSTON — In the bloody aftermath of a shootout between police and two brothers suspected in the Boston Marathon bombing, investigators collected hundreds of spent shell casings, including 56 linked to the same Ruger handgun that had been used to kill an MIT police officer hours earlier, a weapons analyst told a jury on Tuesday.
State Police Lt. David Cahill, testifying Tuesday in the terror trial of Dzhokhar Tsarnaev, said he matched grooves on the 9 mm casings found at both crimes scenes to the Ruger with an scratched-off serial number.
Prosecutors are trying to pin the shootings on Dzhokhar Tsarnaev but defense attorneys argue the Ruger was handled by his brother, Tamerlan, 26, who died in the shootout four days after the April 15, 2013 bombings.
The defense has already conceded Tsarnaev's involvement in the twin blasts that rocked the marathon's finish line, killing three people and injuring dozens. Their goal is to spare him from the death penalty by convincing the jury that Tsarnaev, 19 at the time, was under the influence of his older brother, the mastermind.
A friend of Tsarnaev's testified last week that he lent him a Ruger with an obliterated serial number three months before the bombings and never got it back. Defense lawyers suggested that Tsarnaev had given it to his brother.
A pellet gun was also found at the shootout scene; a fingerprints analyst testified Tuesday that he found Tsarnaev's print on the weapon. He also said Tamerlan's prints were found on a Ruger magazine.
In addition to the 9 mm casings, investigators found 210 casings from bullets fired by the many police officers who cornered the brothers on a residential street in Watertown, Massachusetts, Cahill told the jury.
Tuesday's testimony also included FBI agent Matthew Riportella, who visited a New Hampshire gun range and collected evidence that the brothers had visited less than a month before the bombings. They both shot Glock handguns using 9 mm bullets, Riportella said. He also collected surveillance footage showing the brothers leaving the range.
The day's session ended with another FBI agent, Kimberly Franks, testifying about her search of Tsarnaev's dorm room at the University of Massachusetts at Dartmouth. She said she found a box of BBs and a receipt for a Smith & Wesson BB gun, the same kind found at the shootout scene.
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—Tom Winter, Andy Thibault and Jon Schuppe