corroboration, corroborate - noun
Corroboration: the act of making more certain, the act of corroborating.
A newly released video that was obtained by Britain's Channel 4 and broadcast Monday cast doubt on the government's claims and appeared to corroborate witnesses' stories. The footage appeared to show a gunman and a suspected suicide bomber approaching Bhutto's sport-utility vehicle. Seconds later, the video showed gunfire and Bhutto's hair and scarf being blown back just as a bomb explodes.