Investigators are ramping up their focus on Katherine Russell, the widow of Boston Marathon bombing suspect and alleged planner Tamerlan Tsarnaev after an inspection of her computer turned up radical Islamist material, law enforcement sources said.

With Dzhokhar Tsarnaev, 19, alive and in custody, police are trying to determine what involvement, if any, Russell had in the plot to plant bombs at the finish line of the Boston Marathon on April 15. Russell’s attorney, Amato DeLuca, released a statement earlier this week saying his client was willing to provide “as much assistance to the investigation as she can."

The younger Tsarnaev brother told law enforcement that he and his brother were partly influenced to carry out the attack by the online sermons of Anwar al-Awlaki, an American-born Al-Qaeda speaker who was killed by a US drone strike two years ago. Dzhokhar also said that the brothers learned to make explosives by reading Inspire magazine, an English-language periodical published by Al-Qaeda.

Police sources speaking on the condition of anonymity because of the ongoing investigation said that at least a portion of the radical Islamist material was found on Russell’s computer, although they are trying to determine who exactly accessed the information.

DeLuca has maintained that Russell, 24, had no involvement in the plot. She previously provided a DNA sample after law enforcement officials found female DNA on a component of one of the exploded bombs found in downtown Boston. However, Russell’s DNA was not found on the explosive device.

Federal investigators told The New York Times that they doubt Russell’s innocence, whether in planning the attack or evading police in the aftermath. Russell allegedly called her husband when the FBI released his photograph to the public but did not contact the police. She has reportedly stopped cooperating with authorities.

Russell is known to have worked as many as 80 hours every week as a nurse’s aide while Tamerlan, who was unemployed but sometimes worked as a mechanic, cared for the couple’s child. When he was not taking care of the child, it’s been speculated, Tsarnaev experimented with making bombs using household materials. The police “increasingly believe” the brothers assembled the bombs in their home just five miles from where they detonated them, Reuters reported.

FBI agents spent about 90 minutes Monday looking for evidence at Russell’s parents’ home, where she’s been staying since the attack. The FBI refused to comment on whether they found evidence there. However, it is known that they came up empty-handed Friday after searching four locations near the University of Massachusetts-Dartmouth, where the brothers were thought to have practiced detonations.

Russell was raised in North Kingstown, Rhode Island, where her parents still reside, and met Tamerlan Tsarnaev at Suffolk University. She converted to Islam and married him in 2010. DeLuca claimed Russell does not speak Russian so, often, she could not understand what he was saying when speaking with friends.

The widow has not spoken to the press, but her attorney said earlier this week that Russell had refused to claim Tamerlan's body, instead opting to let his relatives take the corpse.

Rusland Tsarni, Tsarnaev’s uncle, the same who called the brothers “losers” during a media scrum, said Tuesday that he would claim the remains.

“Of course, family members will take possession of the body,” he told the Associated Press. “We will do it. A family is a family.”

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