For more about the disappearance of 6-year-old Etan Patz, a case that frustrated and mystified police for decades, read the story ProPublica produced with WNYC in 2013.

From the moment Pedro Hernandez was arrested for the decades-old murder of Etan Patz, two elemental questions have hung over the controversial case: Was Hernandez’s confession to the sensational killing either reliable or admissible, given what his family and lawyer have asserted is his long history of mental illness?

On Monday, 844 days after Hernandez was arrested and charged in a blaze of headlines and television cameras, the justice system will inch its way closer to a resolution of those questions.

At 10 a.m., on the 7th floor of the courthouse at 111 Centre Street in Manhattan, a hearing is scheduled to explore the circumstances of Hernandez’s confession and the nature and extent of his mental health history.

In strict legal terms, Justice Maxwell Wiley of State Supreme Court will be asked to decide if Hernandez, a retired construction worker who as a teen worked in the SoHo neighborhood where Patz disappeared, was properly advised of his rights during hours of interrogation, many of which were unrecorded. As well, Wiley will have to determine whether Hernandez, given his claims of mental illness and his established history of taking antipsychotic medication, was capable of knowingly waiving his rights – to a lawyer and against self-incrimination.

But the hearing – known formally as a Huntley hearing and expected to unfold over several weeks – may well allow for a broader airing of the government's case, much of which to this point has been kept secret under court seal. Not least, the hearing could permit Hernandez's lawyer to explore a claim he has made in court papers for more than two years: The details of Hernandez's confession do not match the accepted facts surrounding Patz's 1979 disappearance, a shocking story that became the country's most famous missing child case. His body has never been found.

Hernandez, who had been a clerk in a SoHo bodega near Patz's home in 1979, was interviewed by detectives in May 2012 after a family member called in a tip concerning the unsolved case. He was interrogated at a New Jersey police station for seven hours before detectives and prosecutors turned on the cameras to record his confession. Hernandez, in the confession, said he randomly selected Patz as the child stood at a nearby school bus stop, lured him to the bodega basement, immediately strangled him, and then disposed of his body in a box on the city streets.

To date, prosecutors with the office of Manhattan District Attorney Cyrus Vance have publicly disclosed no additional evidence directly tying Hernandez to the alleged murder. They have insisted the confession is credible, and they have openly challenged the claims of Hernandez's mental illness.

Neither prosecutors nor Hernandez's lawyer, Harvey Fishbein, would talk about their strategy in advance of the Huntley hearing. Prosecutors are likely to call the detectives who took the confession to the stand. They are also expected, given court filings in the case, to offer their own expert witness testimony concerning Hernandez's mental capacity.

Fishbein is expected to counter with his own expert witness or witnesses. Fishbein has filed court papers citing the findings of a noted forensic psychiatrist who concluded it would be dangerous to assign any confidence to Hernandez's confession. Over the course of his incarceration – Hernandez has been in custody from the day of his arrest – Hernandez has continued receiving the antipsychotic medication his lawyer maintains he has taken for the better part of the last decade.

Wiley, in a recent ruling, said he would permit both sides to play portions of the various videos made during Hernandez's interaction with detectives. An initial recording was made at the New Jersey precinct house; another was made in Lower Manhattan as Hernandez showed detectives where he said he had left the boy's body; yet another was made in the offices of Manhattan prosecutors.

Which portions of which videotapes get used at the hearing will be closely scrutinized.

The phenomenon of false confessions has surfaced much more prominently in recent years. There have been cases in which suspects have given convincing, detailed, exhaustive, damning – and ultimately false – accounts of crimes they did not commit. The phenomenon has as a result provoked concern about police interrogation techniques.

ProPublica, as part of its months-long investigation of prosecutorial misconduct, wrote at length about the Hernandez case, reporting that there was disagreement in the Manhattan district attorney's office about the wisdom of proceeding with the prosecution of Hernandez.

Most defense lawyers hold out little hope for prevailing in Huntley hearings. Judges often grant wide latitude to police and prosecutors, and the rules of evidence are different than they are at trial. Hearsay, for instance, is admissible in a Huntley hearing.

One of the more memorable Huntley hearings took place during the prosecution of the teenagers charged in the Central Park jogger case. Lawyers for the young men spent weeks trying to discredit the confessions won by detectives in that case as the fruit of coercion, lying and sleep deprivation. The hearing lasted seven weeks, and the judge in the case issued a 100-page ruling. He discounted the claims of coercion and allowed the case to go forward. The teens were ultimately convicted, and each spent some number of years behind bars.

Just this year, after legal challenges, those convictions began to be vacated after a new culprit was identified, and a damning documentary came out. New York City has agreed to pay millions of dollars to the wrongly convicted men.

Wiley, a former Manhattan prosecutor himself, will have great control over how much of the case beyond Hernandez's mental health gets tested during the hearing. But it is not hard to guess at Fishbein's line of attack.

In earlier court papers, Fishbein has seized on what he asserts are provable problems with Hernandez's confession:

Hernandez said he met Patz at the bus stop while over decades of intense investigation by local police and the FBI there has been no evidence shown that the boy even made it to the bus stop that day.

Hernandez said he disposed of Patz's backpack in the bodega basement, but no backpack was ever found despite the bodega being one of the locations most repeatedly searched by investigators in 1979.

Hernandez said he left the box with a possibly still alive Patz on the street in broad daylight, and at a location that was not any kind of designated garbage pickup spot.