While a judge weighs whether a murder confession in one of the nation's most notorious missing child cases can be used at the suspect's trial, a larger question is looming: Was it all made up?

Pedro Hernandez is seen in hours of videotaped statements telling the same unnerving story: How he was a teenage stock boy at a Manhattan convenience store in 1979 when Etan Patz went missing. How he spotted the 6-year-old boy walking to his school bus stop. How he offered him a soda to lure him into a basement. How he began choking him, almost uncontrollably.

"I wanted to let go, but I just couldn't let go," he says. "I felt like something just took over me. I don't know what to say. Something just took over me, and I was just choking him."

His lawyer says the confession is bogus, the result of a mentally ill man who may have been broken down by hours of interrogation that was not caught on tape.

Experts say the 53-year-old Hernandez, who has the IQ of someone with an intellectual disability in addition to a history of mental illness, could be more likely to falsely confess.

Police interrogated Hernandez for nearly eight hours without recording it and prosecutors have pointed to no physical evidence despite repeated searches of his home and the area where he said the crime occurred. And until his name surfaced, a convicted child molester had been widely considered the prime suspect.

But prosecutors stand by the confession. Hernandez — arrested in 2012 after a family member tipped off authorities — admitted three other times in the past three decades that he had killed a child; once to his ex-wife, once to a neighbor and once to a prayer group in New Jersey.

At stake now is a family's search for answers in the baffling case that has spanned decades and continents, and included photos of the boy on milk cartons. His body has never been found, and he remains a symbol of such agonizing cases. May 25, the date he vanished, is National Missing Children's Day.

False confessions happen, but they are hard to quantify. About 15 to 25 percent of known exonerations started with one, said Allison Redlich, a professor at the University of Albany's criminal justice school who studies the phenomenon. In 2006, for example, John Mark Karr confessed to killing child beauty pageant star JonBenet Ramsey in Boulder, Colorado. But DNA evidence quickly exonerated him. The case remains unsolved.

Hernandez's confession videos are a window into his troubled life: He details physical abusive by his father, admits molesting a sister, speaks of seeing his dead mother in a vision and says he rarely sees his son from his first wife.

Redlich says someone with Hernandez' psychological and medical history would be at risk for falsely confessing. She called the length of time he was interrogated before the tapes start rolling "unusually long."

A person being interrogated can even believe in the moment they did something terrible that never happened, Redlich said.

"Police have developed effective techniques to get people to waive their rights and confess," she said. "They are sometimes too effective, because they work on innocent people."

In one of his taped confessions, Hernandez weeps and says he's sorry for having done it. In another, a cellphone video taken by a detective, Hernandez, cigarette in hand, calmly walks the route he claims he took to dispose of the body. He bluntly repeats that he put the boy, still alive, in a bag, put the bag in a box and walked it about two blocks away, stashing it in an alley.

New York City police Detective David Ramirez, who arrested Hernandez, says the suspect felt relieved after finally confessing, and officials say he knows details only the killer would know. Ramirez says Hernandez knew the boy had a book bag, and said he tossed it behind the freezer in the basement. The confession is sensational, but that doesn't mean it's not true, investigators say.

"He said he did it. He was crying, he was weeping," Ramirez said. "We were all taken aback by it, of course."

Hernandez has pleaded not guilty. The court hearing, which continues into a third week Monday, is focused on the narrow question of whether his confession can be used as evidence. A key issue is whether Hernandez was properly advised of his rights and is mentally capable of understanding them. But some scholars believe Manhattan Judge Maxwell Wiley should also consider the reliability of the confession, even though he is not legally required to do so.

"This is central evidence," said University of Virginia Law professor Brandon Garrett, who specializes in false confessions. He said the judge could look at the length of interrogation, mental history and other factors.

"Whether it was rightly obtained matters, but whether it is even reliable to begin with is also an issue that should be considered," he said.

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