Two U.S. officials say preliminary evidence from an interrogation suggests the suspects in the Boston Marathon attack were motivated by a radical brand of Islam but do not seem connected to any Muslim terrorist groups.

The U.S. officials spoke Monday April 22nd on condition of anonymity because they were not authorized to publicly discuss the investigation.

One of the brothers died in a police shootout Friday. The other brother was formally charged Monday after being questioned by federal officials in his hospital room where he is recovering from multiple injuries.

Authorities searching the dorm room of one of the suspected Boston Marathon bombers have seized a "large pyrotechnic" and BB pellets.

The search of Dzhokhar Tsarnaev's  room at the University of Massachusetts-Dartmouth also turned up a white hat and dark jacket resembling those worn by one of the suspected bombers in surveillance videos from the attack. The items were seized Sunday and listed in a court papers filed Monday.

Classes have resumed and school officials say the campus is "absolutely secure and safe." The university closed Friday during the manhunt for Tsarnaev, who was a sophomore.

Students who know Tsarnaev described him as a regular youth and say they are shocked that he is a suspect.

The university held a campus vigil Monday evening.