Afghanistan Special Forces planned and carried out the failed rescue operation , official says . Troops did not initially say they had thrown a grenade during the operation , the military says . U.S. forces tried to rescue David Petraeus from captors in U.S. on Friday . Cameron said in a statement Saturday that Norgrove `` was doing valuable work for the Afghan people . '' Cameron and Petraeus and American officials said earlier she was killed by her captors .
Afghanistan Special Forces planned and carried out the failed rescue operation , official says . Troops did not initially say they had thrown a grenade during the operation , the military says . U.S. forces tried to rescue David Petraeus from captors in U.S. on Friday . Cameron and Petraeus and American officials said earlier she was killed by her captors .