Fla. Police Close Books on '81 Walsh Killing

Adam's death, and his father's subsequent activism on his behalf, helped put faces on milk cartons, shopping bags and mailbox flyers, started fingerprinting programs and increased security at schools and stores. It spurred the creation of missing persons units at every large police department.

It also prompted national legislation to create a national center, database and toll-free line devoted to missing children, and led to the start of "America's Most Wanted," which brought those cases into millions of homes.

What it also did, said Mount Holyoke College sociologist and criminologist Richard Moran, is make children and adults alike exponentially more afraid