The Boston Marathon bombing was perpetrated by two brothers.
On the night of April 18, two men who were riding in a taxi in the vicinity of the shootout were arrested and released shortly thereafter when police determined that they were not involved in the Marathon attacks
 The Tsarnaev brother's uncle, Said-Hussein Tsarnaev, and other members of the Tsarnaev family have repeated this theory, as well as claiming neither brother actually committed the attacks

