Attorneys for the accused Boston Marathon bomber on Wednesday took issue with prosecutors' focus on what they called a "gently mocking" comment about his confinement made by Dzhokhar Tsarnaev to his sister during a jailhouse visit.
An assertion by prosecutors, made in an earlier court filing, that Tsarnaev made a comment "to his detriment" during such a visit is a "red herring" and proof that the 20-year-old suspect could not have normal family visits while being monitored by the FBI, the defense attorneys said.
Prosecutors made mention of the comment in a filing last week when they argued that joint prison visits by Tsarnaev's sisters and attorneys should not be treated as confidential lawyer-client meetings.
Tsarnaev is accused of placing two homemade pressure-cooker bombs at the Boston Marathon finish line last year that killed three people, including an 8-year-old boy, and injured 264 others, and a few days later fatally shooting a university police officer.
He faces the possibility of execution, if convicted.
Defense lawyers argued in a filing in U.S. District Court in Boston that having his meetings with his sisters monitored by an FBI agent working with the prosecution is hindering their effort to gather evidence to argue against the death penalty.
"If Mr. Tsarnaev appears to be lighthearted in his interactions with his sisters, this will be spun into an argument that he should be executed because he lacks remorse," the defense attorneys wrote. "If Mr. Tsarnaev appears impassive or subdued, those observations also likely will be characterized as evidence that Mr. Tsarnaev is cold-hearted and more deserving of the death penalty."
Tsarnaev is being held in a prison west of Boston under special protocol that requires his visits with family members to be monitored.
Prosecutors argue these measures are necessary to ensure that neither the suspect nor his visitors were "soliciting or encouraging acts of violence."
His attorneys said it would be possible instead for a prison guard not affiliated with the prosecution to monitor Tsarnaev's visits from his two sisters without compromising the defense.
Tsarnaev was arrested four days after the bombing attack, when he and his 26-year-old brother, Tamerlan, tried to escape from Boston. The two engaged in a late-night gun battle with police that resulted in the death of Tamerlan.
The Tsarnaev family, ethnic Chechens, emigrated to the United States from the Caucasus region of Russia a decade ago and settled in Cambridge, Massachusetts, where the parents and their four children lived in a small apartment.
After the bombings, sisters Bella and Ailina issued a statement saying they were "devastated" by the attack, which they described as "such a callous act."
A college friend of Tsarnaev's, who is facing trial on charges of obstruction after prosecutors said he removed items from the suspect's dorm room following the bombing, is due in court on Thursday to ask the U.S. government to cover his legal expenses.
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