Boston and Massachusetts law enforcement officials confirmed Thursday that federal agents left them in the dark on the growing warning signs about Tamerlan Tsarnaev in the run-up to the Boston Marathon bombing. 

Boston Police Commissioner Edward Davis, in testimony on Capitol Hill, said his officers on a joint terrorism task force were never told about an explicit warning from the Russian government or about Tsarnaev's travel to the Chechnya region last year. Davis said he would have liked to have known about that activity, and that it "absolutely" would have merited a second look at Tsarnaev. 

Davis and Massachusetts homeland security official Kurt Schwartz testified that their officers were not looped in on Tsarnaev until after the bombing.