(CBS News) Pedro Hernandez is in a New York City hospital this morning on a suicide watch. He was arrested Thursday after confessing to strangling 6-year-old Etan Patz back in 1979.
Now police are looking for evidence to corroborate his confession.
CBS News senior correspondent John Miller reports that the suspect has been arraigned on charges of second-degree murder after confessing to killing Patz. But his lawyer now says his client is mentally ill, bipolar and susceptible to hallucinations.
The suspect appeared in court Friday via closed-circuit TV from a hospital room. Hernandez is being treated for an existing health problem and is under psychiatric evaluation after threatening suicide.
Police say he confessed to strangling the 6-year-old boy in a 3-1/2 hour videotaped statement three days ago.
In 1979 Hernandez was an 18-year-old stock boy at a grocery store just 200 feet from the Patzs' front door.
Police made the arrest after receiving a tip from Hernandez's own family.
A law enforcement source told CBS News that the suspect's brother-in-law, Jose Lopez, was the man who brought the tip to New York City detectives weeks ago, after seeing news reports about police digging up a basement, looking for Patz's body.
Lopez said he has no doubt Hernandez is the killer and that the arrest has been a big relief to the family.
"I don't know what to think, really," Lopez told CBS News. "Somebody we knew, you know, in the family do something like that and just came out now.
"He did the right thing, you know, to confess," Lopez said.
Miller says that now prosecutors have to build their case with police to defend Hernandez's confession, which the defense lawyer has already started attacking with claims of hallucinations and bipolar disease.
"I think that that is Defense 101," Miller said. "You have a guy that gives a clear, compelling, detailed confession, you going to have to either say that he was tricked into doing it or that he was making it up, and I think they're beginning to forge that path."
Miller said that, despite the confession, prosecutors will need more.
"A confession in and of itself is not legally sustainable for a conviction; it needs to be corroborated," he 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'?"
He also said that, beyond a confession and corroboration, juries will seek a motive. "There's something missing in the story here," Miller said. "It's very unlikely that he just lured a boy down to the basement with a soda and killed him for the simple thrill of it, and then went his whole life without a serious crime again. There's probably something else there."
The investigation into the disappearance of Patz was reopened in 2010.
Police were working off a short list of suspects; Pedro Hernandez was not on it.
Etan's parents, Stan and Julie Patz, returned home Friday. Friends tell CBS News that these latest developments in the 33-year-old case are still sinking in.
"I think that they just found out about this person," said news producer Lisa Cohen, author of the book "After Etan." "They've never heard of him over the last 33 years. I think they're taking it in and trying to understand."
When asked if she believes the arrest will finally create a level of peace for them, Cohen replied, "Certainly not right away. I think it's going to raise a whole new level of stress. I mean, they're under siege right now by the press, they're sort of trapped in their home, they're dealing with all of these brand new facts they have never heard before.
"Ultimately, certainly not, you know, total peace. You never get over something like this. But they have always been looking for answers."
To watch the complete report and interview click on the video player above.