WASHINGTON — The F.B.I. did not tell the Boston police about the 2011 Russian warning about Tamerlan Tsarnaev, one of the two brothers accused in the Boston Marathon bombing, the city’s police chief told the first public Congressional hearing on the terrorist attack on Thursday.

Police Commissioner Edward Davis said that though some of his officers worked with the F.B.I. on a joint terrorism task force, they did not know about the Russian tip or the bureau’s subsequent inquiry, which involved an interview with Mr. Tsarnaev and his parents.

Had his department learned about the Russian tip, “we would certainly look at the individual,” Commissioner Davis told the House Homeland Security Committee. He noted that F.B.I. officers found no evidence of a crime and closed the case. He said that he could not say whether he would have reached a different conclusion, but that his officers would “absolutely” have taken a second look at Mr. Tsarnaev.

Speaking with reporters during a break in the hearing, Commissioner Davis praised the F.B.I. but said it was important to examine the failure to share the Russian warning, which said that Mr. Tsarnaev had changed drastically, embraced radical Islam and wanted to travel to Russia to connect with underground groups.

“I’m not ready to vilify anyone at this point in time, but there are questions that need to be answered,” Commissioner Davis said. “And I’m looking forward to the review of what occurred so we can get to the bottom of a lot of different questions.”

The committee’s chairman, Representative Michael McCaul, a Texas Republican who is a former federal counterterrorism prosecutor, said he was concerned that a decision not to share information among different agencies — widely blamed for the failure to prevent the Sept. 11, 2001, terrorist attacks — might have been a factor in the Boston bombings.

“We learned over a decade ago the danger in failing to connect the dots,” Mr. McCaul said. “My fear is that the Boston bombers may have succeeded because our system failed. We can and we must do better.”

Mr. McCaul said he also had concerns that the “emerging narrative” about the Boston plot “downplays the spread of the global jihadist movement.”

“From the attack at Fort Hood to the tragedy at Benghazi, the Boston bombings are our most recent reminder that we must call terrorism really for what it is in order to confront it,” Mr. McCaul said. “You cannot defeat an enemy you refuse to acknowledge.”

Some Republicans have accused the Obama administration of playing down the threat from radical Islam and of exaggerating the administration’s success in reducing the threat from Al Qaeda. On Wednesday, at a politically charged hearing that lasted for almost six hours, Republicans accused the administration of initially trying to cover up the true nature of the terrorist attack last September on the American diplomatic mission in Benghazi, Libya.

The F.B.I.’s investigation of the Boston attack is continuing, but officials have said that so far the evidence suggests that Tamarlan Tsarnaev, 26, who was killed in a shootout after the bombing, and his younger brother, Dzhokhar Tsarnaev, 19, who awaits trial on terrorism charges, were radicalized in the United States and got their instructions in bomb making from the Internet.

But agents are currently in Dagestan, a turbulent area of southern Russia where Tamerlan Tsarnaev spent six months last year, looking into reports that he was trying to connect with Islamist militants who have carried out a campaign of terrorism against Russian forces.

Commissioner Davis said that while more surveillance cameras and other technology may help detect terrorism plots, “there’s no computer that’s going to spit out a terrorist’s name.” People who may pose a threat are probably going to be identified first by others in their own community, he said. Tamerlan Tsarnaev was thrown out of his Boston mosque after outbursts in which he displayed intolerant views, but no one from the mosque contacted the police, Commissioner Davis said.

“We certainly need to engage the community better,” he said.