FBI had grilled Boston bomber in 2011

The United States Federal Bureau of Investigation in 2011 had interviewed one of the two Chechen-origin Boston bombings suspects, who was killed after a massive manhunt, but apparently let him out of their sights after not detecting any terrorist activity.

Agents in 2011 interviewed Tamerlan Tsarnaev, suspected of being behind the deadly bombings in Boston that claimed three lives and injured over 180, at the request of a foreign government that suspected he might have ties to extremist groups, the FBI said on Friday.

Tamerlan was pronounced dead on Friday morning after suffering shrapnel and bullet wounds in a gunfight with police, while his 19-year-old brother Dzhokhar Tsarnaev, also a suspect, was later arrested in connection with the bombings.

Both suspects were brothers from a Russian region near Chechnya, which has witnessed deadly bombings carried out by Islamic rebels.

"The request (by the foreign government) stated that it was based on information that he was a follower of radical Islam and a strong believer," the FBI said, "and that he had changed drastically since 2010 as he prepared to leave the US for travel to the country's region to join unspecified underground groups."

An FBI official declined to name the foreign government, but said the FBI took a number of investigative steps to check on the request, including looking at his travel history, checking databases for derogatory information and searching for Web postings.

Agents also interviewed Tsarnaev's family members, the FBI said, but did not detect terrorist activity.

"The FBI did not find any terrorism activity, domestic or foreign, and those results were provided to the foreign government in the summer of 2011," the FBI's statement was quoted by CNN as saying.

"The FBI requested but did not receive more specific or additional information from the foreign government," it said.

Chairman of the House Homeland Security Committee Michael McCaul said on Friday that information that Tsarnaev had been interviewed by the FBI in the past was disturbing.

"It's new information to me and it's very disturbing that he's on the FBI's radar screen," McCaul said.

"But if he was on the radar and they let him out of their sights, then that's an issue, certainly, for me," McCaul said.

The suspects' parents also told Russian state media that the FBI had been speaking with their sons.

"FBI came to them two or three times, asking 'Are you Chechens? Is anyone harassing you?' Why would anyone offend us? Then they came again. Said they wanted to talk to Tamerlan," father Anzor Tsarnaev told the state-run RIA Novosti news agency.

"We didn't know what was going on, didn't know whether he had done something. But they were saying, 'Oh, it's nothing, it's just routine.' They talked to us at our home," he said.

Mother Zubeidat Tsarnaeva told Russia Today that the FBI had been checking on Tamerlan for three to five years.

"They knew what he was doing, what sites he was visiting. They followed his every move, yet today they say this is a terrorist act," she said.