WASHINGTON - Amid disclosures that Russia tipped the FBI in 2011 that one of the Boston Marathon bombers had become a Muslim radical, Republican leaders of the House Homeland Security Committee plan to hold hearings to examine what the bureau and U.S. intelligence agencies might have done to thwart last week's attack.

The committee's chairman, Texas Rep. Michael McCaul, and New York Rep. Peter King, a key subcommittee chairman, asserted that the elder of the two Chechen brothers implicated in the Boston attacks appeared to be the fifth person since Sept. 11, 2001, "to participate in terror attacks" after being interviewed by the FBI.

Across Capitol Hill, Sen. Dianne Feinstein, D-Calif., who chairs the Senate Select Committee on Intelligence, has asked FBI officials to appear before her panel on Tuesday to talk about the Russian tip about Tsarnaev.

The House Republican demands contrasted sharply with praise being heaped on the bureau and other law enforcement agencies for identifying and tracking Tsarnaev and his 19-year-old brother, Dzhokhar, within days of the attacks, underscoring the seesaw public relations battle facing those agencies in the ebbs and flows of terrorism.

Details are still emerging about Tamerlan Tsarnaev's activities prior to the attacks, and the bureau's investigation is sure to be dissected closely, though the disclosures to date suggest that even a misspelled name could have foiled the bureau's attempts to stay abreast.

In the latest grisly revelation, the Boston Globe reported Monday that a friend of Tamerlan Tsarnaev's, 25-year-old Brendan Mess, was among three young men whose throats were slit, apparently on the night of Sept. 11, 2011, the 10th anniversary of the 2001 terror attacks on New York and Washington. Those murders haven't been solved.