Robert McKenna spent more than two decades with the New York City Police Department, but he has no trouble remembering the days and nights of late May 1979, when much of the city was consumed by the disappearance of a 6-year-old Manhattan boy who had gone missing while headed to school alone for the first time. McKenna, then a patrol officer, was one of a small army of officers knocking on doors in the SoHo neighborhood, shining flashlights behind dumpsters, questioning potential witnesses.

McKenna said he has particularly vivid memories of the bodega that stood on the corner of Prince Street and West Broadway, where the boy's school bus stop was also located. The police had been told that the boy, Etan Patz, might have stopped at the bodega to buy a soda that morning. 

"There was a register at the front of the store, a refrigerator full of soda in the back and a wide open floor," McKenna recalled.

McKenna said the bodega served as something of a command post for the police department's search. And he remembers talking with a female officer who had searched the bodega's basement.

 "She was a mother of two, I believe, so she was very concerned about this little boy," McKenna said in an interview this week. "She told me she'd checked everywhere, every nook and cranny of the basement."

Nearly 36 years after Etan Patz vanished, a former clerk at the SoHo bodega was tried on charges that he committed the boy's murder. Pedro Hernandez, 18 years old in 1979, confessed in 2012 to having strangled the boy in the store's basement, packed him up in a box and tossed the boy's book bag behind a refrigerator. The trial ended with a hung jury, a dozen people who spent 18 days unsuccessfully trying to reach unanimity. When State Supreme Court Justice Maxwell Wiley formally declared a mistrial on May 8, the jury was split 11-1 for conviction.

In interviews with reporters for New York newspapers and television stations, jurors described long debates about a range of issues that had come up during the trial: whether someone could be convicted on the basis of a confession alone; whether a convicted pedophile who had long been considered the chief suspect in the case was the more likely killer; whether Hernandez, as his lawyers had maintained, was severely mentally ill, and his confession an imagined fiction.

The debates, the jurors, said, also included lengthy discussion of the bodega, and whether it had been properly searched. If it had, wouldn't the police have found the book bag?

Adam Sirois, the lone holdout juror in favor of acquittal, said the debate about the bodega became heated.

"It doesn't add up that they wouldn't have found that bag," Sirois said in an interview with the New York Post. He added, "You almost have to want him to be guilty, in my opinion, to say the police could not have searched the bodega basement. It's right at the bus stop where he was headed. "

In an interview Wednesday with ProPublica, Sirois repeated his bafflement.

"If you believe that they didn't search the bodega top to bottom, then it's just not rational," he said.

McKenna did not testify at the trial. But he had told a version of his account to ProPublica in 2013 and it was included in an extensive examination of the case against Hernandez.

ProPublica contacted McKenna after the trial, and after the jurors had begun to detail their deliberations.

"I salute Adam Sirois," McKenna said. "He prevented what would've been a horrible miscarriage of justice."

The case against Hernandez has been controversial from the time he was arrested and later charged with murder by Manhattan District Attorney Cyrus Vance. Vance said Hernandez's confession was authentic, and supported by other evidence. Hernandez's lawyer has argued that the confession was coerced by detectives acting on a tip that Hernandez might have killed Patz.

Some prosecutors within Vance's office thought it was a mistake to go to trial. A former federal prosecutor who spent years on the Patz case actually testified during the trial that he believed the convicted pedophile, a man named Jose Ramos who had been a boyfriend of a Patz family babysitter, was the killer. An expert called by the prosecution testified that Hernandez's mental issues were not terribly significant. A competing expert called by the defense testified that Hernandez's illness was real, and that his account of the killing could not be trusted.

The accounts of the jurors make clear they worked hard to assess any evidence that might corroborate Hernandez's confession. Several people had testified that Hernandez, in the years after Patz's disappearance, had talked about once having harmed or killed a child in New York. The defense, meanwhile, had sought to demonstrate that the details of Hernandez's confession did not match some of the long-accepted facts surrounding the boy's disappearance.

Sirois, in an interview Wednesday, said McKenna's account, if it held up to scrutiny, would have been helpful – at least on the troubling question of whether the bodega basement had been adequately searched. No police account introduced at trial, in testimony or through department records, unequivocally stated the bodega basement had been searched.

"That could've changed everything," he said when told of McKenna's account.

Sirois said some jurors were troubled that the police records documenting the search for Patz didn't specifically state that the bodega basement had been searched. He said they were unwilling to infer that it would have to have been searched. He said he had pressed hard. The boy's mother, Julie Patz, had testified at the trial that her son had been headed to the bodega. Wouldn't she have insisted the bodega be searched, Sirois said he asked his fellow jurors.

Vance has not said whether prosecutors will seek to retry Hernandez. Fishbein, the defense lawyer, said he is prepared to make his case again. Inevitably, if there is another trial, both sides will use the accounts of the jurors as they seek to strengthen their arguments.

Joan Vollero, a spokeswoman for Vance's office, noted that the bodega was not located within what investigators at the time referred to as the "core zone" of the hunt for Patz. She maintained that McKenna's description of the scene at the bodega was contradicted by the testimony during the trial of the store's manager, Santana. But she would not publicly detail those contradictions.

Fishbein, Hernandez's lawyer, said Santana's testimony at trial was that he could not remember whether police had searched the bodega the first night of the boy's disappearance, perhaps because he customarily left the store in the early evening. Santana, Fishbein noted, did testify that he remembered police searching the bodega, including the basement, days later.

McKenna, for his part, said he would have "no problem about testifying."

McKenna said he retired from the police department in 1997, with the rank of lieutenant. He said he has since worked as a private security consultant and sometime actor.

In May 1979, McKenna said he was 27, and had been back on the force for a year after being laid off during the fiscal crisis in 1975. He said he was part of a "neighborhood stabilization unit" that could be assigned anywhere in Manhattan. He produced his department-issued memo book from 1979 that showed he reported to the SoHo neighborhood to aid in the search for a lost boy at 2200 hours May 25.

McKenna said there were officers everywhere during the first night of Patz's disappearance. He said as many as twenty officers were in the bodega at any one time. He said he didn't himself go into the basement, but that a female officer had, perhaps with another officer. He said he spoke with the female officer in a police van afterward.

"In the van, she told me, 'I checked everywhere, I didn't see anything,'" McKenna said of the officer. He struggled to remember the officer's name, but thinks her first name was Fran.

Hernandez, in his confession, said he lured Patz to the basement from the bus stop with the promise of a soda. The basement was accessed by an entrance on the sidewalk outside the bodega. Hernandez said he choked the boy, then packed him, still alive, inside a bag and then a box. He then shouldered the box and walked it several blocks away in the broad daylight of an early May morning.

Three decades later, McKenna said he still has a clear sense of how the bodega was run, and he said he is openly skeptical that Hernandez could have done what he said he did. He said the managers of the bodega "saw everything that went on." He claimed the sidewalk entrance to the basement was visible from the register. He said the people who ran the bodega would never have allowed Hernandez to take a boy to the basement. During the trial, the bodega manager, Juan Santana, said the entrance was routinely kept locked and that it was unlikely Hernandez could have gained access.

Said McKenna: "Even if he did, he comes back with a bag over his shoulder? Absolutely no way."

Sirois understands McKenna's doubts. The boy's book bag, he said, was actually an open-ended tote bag full of cars and toys. He said Hernandez's description of having flung it on or over the refrigerator in the basement suggested the toys should have fallen out.

Sirois said he was bothered by one other aspect of the case against Hernandez. Prosecutors have argued that Hernandez, after briefly returning to the bodega after having put the box with the boy inside in a nearby alley way, fled New York for his family in New Jersey. Why, then, Sirois asked, didn't Hernandez come back to dispose of the bag? Or if he did, why didn't he confess to that, as well?

"He never put in his story that he goes back and removes the bag," Sirois said of Hernandez. "If it's a full confession to something he did, it doesn't make sense for him to leave that out. He doesn't have that kind of intelligence— to confess to a story and leave out damning evidence that would exonerate him."