Boston Bombing Suspect Watch: Police Find Circuit Board Used to Detonate Bombs

According to the Boston Globe, authorities have recovered what they believe to be a circuit board that was used to detonate two explosive devices placed near the finish line of Monday's Boston Marathon. Those explosions killed three people and injured more than 170, with more than ten people requiring amputations. 

The bombs were made using two six-liter metal pressure cookers, which were loaded with shrapnel, including nails and ball bearings, and placed in duffel bags. The bombs exploded approximately 12 seconds, and 75 to 100 yards, apart. 

The explosions killed 8 year-old Martin Richard of Dorchester, 29 year-old Krystle Campbell of Arlington, and a third person whose identity has not been disclosed. 

On Monday night Boston and Revere police, as well as federal investigators spent several hours at an apartment complex in Revere, Massachusetts, questioning the roommates of a Saudi national recovering from blast-related wounds at a Boston hospital. Authorities have said neither the man in the hospital or his roommates are suspects, and that all were cooperating with law enforcement.