President Barack Obama defended the FBI's 2011 investigation into one of the suspects in the Boston Marathon bombings.

At a news conference today, Obama dismissed criticizms that the agency didn't do enough when it received information from Russian authorities about 26-year-old Tamerlan Tsarnaev.

"It's not as if the FBI did nothing," he said. "They not only investigated the older brother; they interviewed the older brother. They concluded that there were no signs that he was engaging in extremist activity."

The Office of the Director of National Intelligence is conducting a review of law enforcement's handing of information about Tsarnaev and his brother, 19-year-old Dzhokhar, prior to the attacks.

Russian officials contacted U.S. authorities because of concerns that Tamerlan Tsarnaev was becoming increasingly an radicalized Islamist. A CIA request placed Tamerlan on a watch list for potential terror suspects.

"When an event like this happens, we want to go back and we want to review every step that was taken," Obama said. "We want to leave no stone unturned. We want to see, is there in fact additional protocols and procedures that could be put in place that would further improve and enhance our ability to detect a potential attack?"

Dzhokhar was charged last week in connection with the April 15 bombings that killed three people and wounded more than 260. Tamerlan died trying to escape from authorities.

Obama said that based on what he knew so far, "the FBI peformed its duties; Department of Homeland Security did what it was supposed to be doing."

Report: Tsarnaev family got $100k in benefts

The Tsarnaev family received more than $100,000 in welfare assistance, the Boston Herald is reporting.

Massachusetts lawmakers are investigating the cash, food stamps and housing assistance the family received.

"The breadth of the benefits the family was receiving was stunning," a person with knowledge of documents given to a legislative committee told the newspaper.

A panel is reviewing more than 400 pages of documents from state agencies that provided benefits to the bomb suspects or their families since 2002, according to the Associated Press.

Female DNA found on bomb

Female DNA was found on one of the bombs that exploded at the Boston Marathon finish line and law enforcement officials are investigating the wife of one of the suspects, according to news reports.

Officials briefed on the case told the Wall Street Journal that investigators haven't determined whose DNA was found on the bomb or whether it means the brothers had help.

The genetic material could have come from a store clerk or a stray hair, rather than from a co-conspirator.

Still, the FBI is scrutinizing Katherine Russell, Tamerlan Tsarnaev's widow.

Special Agent Jason Pack told the Washington Post that agents spent about 90 minutes at her parents' Rhode Island home, where she has been staying, on Monday. Authorities took a sample of her DNA, according to the New York Times.

Russell has not spoken publicly since the explosions. Her lawyer, Amato DeLuca, told the Times in an email Monday that, "We want to state what we stated before: Katie continues to assist in the investigation in any way that she can."

Death-penalty expert joins defense

Judy Clarke, a prominent death-penalty attorney, is joining Dzhokhar Tsarnaev's defense team.

A federal judge approved the San Diego lawyer's appointment on Monday, the Associated Press reports.

Clarke's past clients have included Unabomber Ted Kaczynski; Tucson, Ariz. shooter Jared Loughner; and Susan Smith, who drowned her two children. They all were sentenced to life in prison instead of receiving the death penalty.

Link to slain Canadian jihadist?

Investigators are reportedly examing potential links between Tamerlan Tsarnaev and William Plotnikov, a Canadian boxer-turned-jihadist who was killed last year by Russian forces.

Two Russian government officials told the WSJ that Tsarnaev exchanged messages online with Plotnikov, who moved from Russia to Canada before becoming a militant in the North Caucasus.

CNN reports that Plotnikov and six others were killed in a fight with Russian troops in Dagestan iin July, while Tsarnaev was in the region. Investigators are trying to determine if Tsarnaev, who left the region two days later, departed because of Plotnikov's death, or if he was in contact with Mahmoud Mansur Nidal, another slain militant who died last May.

Cause of bomb suspect's death determined

A medical examiner has determined how Tamerlan Tsarnaev died, but not released the findings.

The AP reports that the medical examiner won't say how he died until his remains are released and a death certificate is filed.

Tamerlan died after a gunfight with police; authorities have also said he appears to have been dragged under a vehicle driven by Dzhokhar during the getaway attempt.

Contact Emily Babay at 215-854-2153 or Follow @emilybabay on Twitter.
Contact the Breaking News Desk at 215-854-2443; Follow @phillynews on Twitter.