Bishop had been inspired by the September 11 attacks; he had left a suicide note crediting Osama bin Laden for the attacks and praising it as a justified response to actions against the Palestinians and Iraqis and said he (Bishop) was acting on behalf of Al Qaeda, from whom he had turned down help. As officials could find no other evidence of any connections, terrorism as a motive was ruled out, and they suggested that the crash was an apparent suicide. Bishop's mother filed, then dropped, a lawsuit claiming that psychological side effects from isotretinoin, an acne medicine Bishop took, which can include depression and rarely suicidal actions, caused the incident.