WASHINGTON — As investigators sought answers to what or who may have radicalized the suspects in the Boston Marathon bombings, leading lawmakers said Tuesday that potentially important clues about at least one of the men might not have been widely shared within investigative circles months before the attack.

Emerging from a closed two-hour hearing with three senior law enforcement and intelligence officials, several members of the Senate Intelligence Committee raised new questions about how the F.B.I. and the Department of Homeland Security apparently handled information about Tamerlan Tsarnaev, 26, the suspect who was killed in a shootout with the police on Friday.

“I’m very concerned that there still seem to be serious problems with sharing information, including critical investigative information,” Senator Susan Collins, Republican of Maine, told reporters. “That is troubling to me that this many years after the attacks on our country in 2001, that we still seem to have stovepipes that prevent information from being shared effectively, not only among agencies but also within the same agency, in one case.”

Senator Saxby Chambliss, a Georgia Republican who is the committee’s vice chairman, also voiced worries that efforts to break down barriers of communication between federal intelligence and law enforcement agencies after the Sept. 11, 2001, attacks may have started to erode. “There have been some stone walls and stovepipes reconstructed that were probably unintentional,” he said. “We’re going to continue to look at whether or not all the information was adequately shared and given to all the law enforcement agencies. If it wasn’t, we’ve got to fix that.”