Military officials explained this as saying they had to estimate detainee ages. :"They don't come with birth certificates," said Col. Brad K. Blackner, the chief public affairs officer at the detention camp. Col. David McWilliams, the chief spokesman for the United States Southern Command in Miami, which runs the prison operation, said that the authorities were fairly confident of their estimates. "We used bone scans in some cases and age was determined by medical evidence as best we could," he said."