Additional reporting by Jon Schuppe and Andy Thibault
Accused Boston Marathon bomber Dzhokhar Tsarnaev's defense lawyers rested their case Tuesday after trying to shift jurors' focus onto his older brother, Tamerlan, who they say masterminded the April 15, 2013 attack. Juror deliberations will begin Monday after closing arguments.
The defense called a total of just four witnesses over two days, all evidence gatherers. On Tuesday an FBI agent testified about finding Tamerlan' Tasrnaev's fingerprints on materials used to plan and carry out the marathon bombings and used in an assault on police four days later.
The strategy is relatively straightforward: with a guilty verdict all but assured, Dzhokhar Tsarnaev's lawyers are trying to spare him from the death penalty by portraying him as a manipulated apprentice. If Tsarnaev, 21, is convicted, the trial will move to the death penalty phase.
On Tuesday, the defense also called computer forensic analyst Mark Spencer, who inspected digital evidence taken from the brothers' laptops. He said he found Internet searches for the Boston Marathon, gun stores, wireless transmitters, detonators and a "fireworks firing system" on a laptop the defense says was Tamerlan's. There were no such searches on Dzhokhar's device, Spencer said, except for a search for the marathon after the bombings.
Spencer also said that copies of the al Qaeda associated magazine Inspire — including an article called "Make a Bomb in The Kitchen of Your Mom," which prosecutors highlighted earlier in the trial — were created on Tamerlan's computer then transferred via thumb drive to Dzhokhar's.
But under questioning from Assistant U.S. Attorney Aloke Chakravarty, Spencer acknowleged that it was impossible to know who was using either of the laptops at any time.
Later, FBI fingerprint examiner Elaina Graff described finding Dzhokhar's prints on a plastic container containing fuse and gunpowder found at the scene of a shootout with police in Watertown, Massachusetts, where Tamerlan was killed. But that was about the only place where she said she lifted his prints. Tamerlan's, on the other hand, were found on a transmitter, a pressure cooker lid, a jar of nails, a caulking gun, rolls of duct tape and a soldering iron, Graff said.
But under cross examination, Graff also said that many fingerprints could be destroyed in an explosion, that the absence of a fingerprint on an item didn't necessarily mean someone hadn't touched it.