(CBS News) NEW YORK - The man charged with killing 6-year-old Etan Patz 33 years ago is spending his first weekend in jail following his surprise arrest on Thursday, but despite the apparent confession of Pedro Hernandez, not everyone is convinced police have their man.
Eight years ago, a Manhattan judge ruled that Jose Ramos, a convicted pedophile, was responsible for Patz's death, but Ramos was never charged with murder.
"Investigators both from federal prosecutors' office and the FBI over an extended period of time built up a tremendous amount of circumstantial evidence," said Murray Weiss, a police reporter who covered the Patz case.
Not enough, though, to convince prosecutors they could make a murder charge stick. It was a civil case that resulted in the judgment against Ramos. He was ordered to pay $2 million in damages to the Patz family. He has no money and is in prison for molesting a Pennsylvania child.
The Ramos case raises serious questions about the recent arrest of Hernandez, 51. Police say he confessed to murdering Patz but they have no evidence.
It is in fact a murder case standing on its head.
"It's going to be very difficult to convince a jury," said Larry Kobilinsky, a doctor of forensic science at John Jay College of Criminal Justice.
"Normally we collect the physical evidence and talk to the witnesses; then we catch a suspect, interrogate him and then sometimes they confess," said Kobilinsky. "This is just the reverse."
Police have no body and no motive, and what happens if Hernandez recants his confession?
"It would not surprise me if Pedro Hernandez recants," said Kobilinsky. "After all, look at what he's facing. If he's convicted of second-degree murder, he's going to spend his entire life, perhaps, in prison."
Right now, Hernandez remains in Bellevue Hospital awaiting a psychiatric exam to determine if he is competent to stand trial for murder.