According to NYTimes:

Late Monday night, law enforcement officials descended on an apartment building in the suburb of Revere, about five miles north of Copley Square, linked to a man the police took into custody near the scene of the bombings. But on Tuesday morning, one law enforcement official said investigators had determined that the man, who was injured in the blast and was questioned at the hospital, was not involved in the attack.

Saudi connection may be evaporating.