WASHINGTON (AP) - The Boston police commissioner says three city police officers were working with the US terrorism task force but did not know about vague warnings by Russia's government about one of the bombing suspects delivered nearly two years before the attacks.

Commissioner Edward Davis says he would have liked to known that Russian authorities had warned the FBI that Tamerlan Tsarnaev was a radical extremist before the April 15 attacks.

Comissioner Davis, testifying at a hearing on the attacks, said on Thursday that he can't say exactly what police would have done with that information. But he said police likely would have at least looked closely at Tsarnaev.

Former Senator Joseph Lieberman told lawmakers more threat information should be shared with state and local police, who he called "your first line of defence".