Rep. Peter King questions FBI's 2011 investigation of Tamerlan Tsarnaev

The FBI is facing scrutiny over how it decided a Boston Marathon bombing suspect had no terrorist links after agents questioned him less than two years ago.

Tamerlan Tsarnaev, 26, killed early Friday in a shootout with police, was interviewed by bureau agents in summer 2011 at the request of a foreign government, identified by a federal law enforcement source as Russia. The FBI found no links to terrorism and released him.

Rep. Peter King (R-Seaford), a member and former chairman of the House Homeland Security Committee, fears the FBI might have missed something. "Did they move too quickly by letting this guy off the hook?" King said in an interview. "Should they have looked more carefully?"

King said he and Homeland Security Committee chairman Michael McCaul (R-Texas) are drafting a letter to U.S. Attorney General Eric Holder and FBI Director Robert Mueller, requesting a classified briefing on the 2011 interview with Tsarnaev.

King said he wants to know "what information was given and what was done with it."

King noted that on two occasions the FBI interviewed or investigated people who went on to commit terror acts on U.S. soil in 2009: Abdulhakim Mujahid Muhammad, who is serving a life sentence for killing an Army private at a Little Rock, Ark., recruiting station, and Army Maj. Nidal Malik Hasan, charged with killing 13 people at Fort Hood, Texas.

In a statement issued Friday, the FBI said it investigated Tsarnaev after receiving intelligence from a foreign government that he was "a follower of radical Islam" and "that he had changed drastically since 2010." That foreign government feared Tsarnaev was preparing to travel to that country to join "underground groups."

A federal law enforcement source said Russia was concerned about Tsarnaev's possible links to Chechen extremists. He and the second suspect in the Boston attack, his brother Dzhokhar, 19, were immigrants from a Chechen family.

Fighting between Russia and separatists in Chechnya, a largely Muslim region, has killed thousands since the 1990s.

Zubeidat Tsarnaeva, the mother of the two suspects, told Russia Today television that Tamerlan was under FBI surveillance for several years.The FBI said it checked federal databases, looking for "derogatory telephone communications, possible use of online sites associated with the promotion of radical activity, associations with other persons of interest, travel history and plans, and education history."

As agents investigate the Boston bombings, they are seeking more information about what led to the initial Russian request, the source said. Security consultant Robert Strang, who runs the Investigative Management Group in Manhattan, said it's common for countries to share intelligence about possible terrorism suspects. But he said detecting links to terrorism is difficult if a person is working on his or her own or as part of a small cell operating inside the United States.

Authorities said Tsarnaev spent seven months in Russia from January to July 2012, but little is known about the trip.