The suspect, Pedro Hernandez, was arrested this week after a relative reported he had talked of killing a boy. He was being held in a hospital on suicide watch.
When Etan disappeared on his way to the school bus stop in 1979, Hernandez was an 18-year-old stock clerk in a store near the boy's home.
"A confession in and of itself is not legally sustainable for a conviction; it needs to be corroborated," CBS Senior Correspondent John Miller said. "How often did he make these statements? To how many family members? What exactly did he say, and over how many years? Are there people who worked in the store with him back then who remember on this day 'I remember he disappeared for half an hour and when he came back I said, 'Where were you' and he said X'?"
Hernandez has a history of mental illness, and family members say he has been known to hallucinate. Miller said the lack of a motive and Hernandez's apparently crime-free life since 1979 may be problematic for prosecutors.
In his confession, Hernandez said he lured Etan to the basement of the store where he worked with a soda, killed him and then dumped the body in the trash.