 The plan was to use the hostage officers as cover as the prisoners made their way to the dock, then San Francisco and freedom.Miller had held on to the yard door key (against regulations), so that he could let out kitchen staff without having to disturb the gallery officer at lunch.Although they eventually found the key by searching the captive officers and the cell in which the prisoners had placed them, the door would not open because the lock had jammed as the prisoners had tried several other keys while searching for the correct one.