in boston i'm stacey cohan reporting. >> federal agents confirm that the f-b-i interviewed the older brother, tamerlan tsarnaev in 2011, after being tipped off by a foreign government. the suspect identified himself as ethnic chechen from southern russia and officials there believed tamerlan was going to travel to the country's region to join unspecified underground groups. the fbi says it interviewed tsarnaev and relatives, and did not find any domestic or foreign terrorism activity. meanwhile, tsarnaev's uncle says he had a falling-out with the 26-year-old over his increased commitment to islam. boston cardinal sean o'malley is dedicating mass today to the bombing victims. it's being held at the city's holy cross cathedral, where president obama attended a ceremony earlier this week. cardinal o'malley also plans to celebrate the tragedy's first responders. afterwards, parishioners will gather for a victims' memorial near the marathon finish line. a solemn salute in boston for murdered m-i-t police officer sean collier. people joined many of boston's finest last night for funeral se