Kindergarten Police Station

Little Johnny's kindergarten class was on a field trip to their local police station where they saw pictures, tacked to a bulletin board, of the 10 most wanted men. One of the youngsters pointed to a picture and asked if it really was the photo of a wanted person.
"Yes," said the policeman. "The detectives want him very badly."
Little Johnny asked, "So, why didn't you keep him when you took his picture?"