The CIA had detected an "apparent Western hostage" in Al-Qaeda custody in Pakistan but did not keep him under drone surveillance before—U.S. officials now believe—he was accidentally killed by a drone strike in January. The Washington Post reported Thursday that the captive in question may have been American aid worker Warren Weinstein. U.S. officials allege that the initial drone footage they had indicating a hostage may have been present was not good enough to ascertain whether it was Weinstein. "The CIA had watched the site for 400 hours before launching the strike," the Post reports, "which also killed senior al-Qaeda leader Ahmed Farouq, a U.S. citizen." An internal CIA investigation is ongoing in Weinstein's death.