Attorneys for the former bodega clerk convicted last week of murdering 6-year-old Etan Patz in 1979 are exploring whether the jury was exposed to improper information during the course of the four-month trial and prior to deliberations.

After the Manhattan jury reached a unanimous guilty verdict last week, Newsday reported that a juror from the trial — the second brought against 56-year-old Pedro Hernandez — had been told by a court officer that one or more jurors from the first trial were attending the second proceeding, where they sometimes sat with the dead boy’s father, Stan Patz.

The first trial involving the disappearance and death of one of the most famous missing children in American history ended in a hung jury in May 2015. But afterward many jurors spoke passionately and publicly of their belief that Hernandez was, in fact, guilty. Several forged relationships with the Patz family and Manhattan prosecutors.

During the second trial, Judge Maxwell Wiley made efforts to prevent jurors from knowing there had even been a first trial. Lawyers on both sides were barred from mentioning it specifically and instructed to refer to any of its events as “prior proceedings.”

Harvey Fishbein, one of Hernandez’s attorneys, said he understood the Newsday report to mean that the juror had been informed by the court officer prior to deliberations and he has sent investigators to speak with jurors from the second trial. He said he would soon ask the judge to order a hearing into what he called “the extent of the jury contamination.”

"We were instructed by the judge not to mention a first trial,” Fishbein said. “The judge did not want jurors to know that.”

The Newsday story described an emotional scene outside the courthouse after last week’s conviction. Jennifer O’Connor, a particularly outspoken juror from the first trial, embraced Michael Castellon, a juror from the second trial.

Asked by Newsday how the pair knew each other, Castellon said that a court officer had told the jury that jurors from the first trial were attending the second. Castellon did specify when that exchange happened or if anyone else heard it.

However, Castellon did try to take his comment back. According to the Newsday story, Castellon twice asked that his comment not be reported. Then he walked away from a cluster of reporters. Castellon, who has a law degree from Duke University, did not respond to repeated messages from ProPublica.

Castellon was one of several jurors who stayed in the courtroom after the verdict to talk with reporters. He spoke at length about the deliberations and the evidence they weighed, calling them thoughtful and logical. He described the evidence presented by Fishbein as the equivalent of throwing spaghetti against the wall.

The Manhattan District Attorney’s office was notified of Castellon’s claim by Newsday after the verdict and declined to comment on it. ProPublica inquired about the matter separately and got the same response.

ProPublica also asked a spokeswoman for the district attorney whether the office’s knowledge of the Castellon claim required it to notify the court. The spokeswoman would not answer.

“They have an obligation to investigate,” Fishbein said of the prosecutors. “And I hope they have a desire to.”

ProPublica spoke with one juror from the second trial. To that juror’s knowledge, no one on the panel was aware of jurors from the first trial being in the courtroom.

Joel Cohen, a Manhattan attorney who regularly writes on ethics for the New York Law Journal and other publications, told ProPublica that a hearing conducted by the trial judge would likely be the most appropriate course of action.

“The issue is probably best explored in a balanced way by a hearing,” Cohen said in a phone interview. “The district attorney obviously has a vested interest in preserving the conviction and the better way to assure a balanced view of what did or didn’t happen is a public hearing where Hernandez’s lawyer can examine fully what the facts are. As they say, cross-examination is the greatest legal engine ever invented for the discovery of truth.”

Etan Patz went missing on the morning of May 25, 1979, on the way to his school bus stop. Hernandez surfaced as a suspect 33 years later in 2012. He was arrested and charged after his family members contacted law enforcement, saying he had, over the years, rambled something of a confession to the crime.

After a seven hour, unrecorded interrogation, Hernandez told police he had lured the boy down into the basement of a bodega where he worked, strangled him, put him in a bag while he was still alive, put the bag in a box and carried it to an alley blocks away from the bodega in broad daylight.

Hernandez’s defense attorneys say his confession is a fiction. It was produced, they say, by a mentally ill man with a low IQ, who had been subject to a long, improper police interrogation.

There has long been a split opinion about whether Hernandez is the true killer. Federal officials have privately expressed skepticism about it. Many believe that another suspect named Jose Ramos, the former boyfriend of the boy’s babysitter and a convicted child molester, is the real perpetrator. Mary Galligan, a former FBI agent on the case, testified at both trials about her belief Ramos is the killer.

When Manhattan District Attorney Cyrus Vance first announced his decision to pursue a case against Hernandez, some prosecutors within his office worried it was a mistake.

The first trial went on for several months in 2015 and ended after 18 days of deliberations. Adam Sirois, the lone holdout on the jury, said at the time that he found Hernandez’s confession “bizarre” and could not get past reasonable doubt.

Several of those who supported a guilty verdict openly criticized Sirois, calling him arrogant and accusing him of using his position on the jury as a way to attract attention. The jurors in favor of conviction took up the cause to retry Hernandez, appearing in court the first day the district attorney petitioned for a second trial.

They clearly worked with prosecutors to prepare for the second trial. The defense worked with Sirois, the holdout, and interviewed some number of jurors who had voted to convict. None of that contact is particularly unusual. In such circumstances, former jurors often work with one side or another.

The American Bar Association has guidelines for prosecutors and defense attorneys talking with jurors after a trial, cautioning them against discussing a “case with jurors after trial in a way that is critical of the verdict.”

ProPublica attempted to reach members of the first jury to discuss their work with the prosecution and the defense. Few responded. One juror who did appeared to speak for a group, telling ProPublica “we are not going to speak with you” in an email.

The jury from the first trial certainly established an unusual level of camaraderie with one another and the Patz family. O’Connor and other members of the first jury held a memorial for Etan Patz at the scene of his disappearance on National Missing Children’s Day in May 2015. At the time, one of the jurors told The New York Times the meeting was “important for the next trial.”

“It’s important to show the defense that we so strongly believe that Pedro is guilty,” the juror said.

Several members of the first jury went on to regularly attend the second trial. One person who spent weeks at the trial said two of the former jurors were there constantly, seated close to or next to Stan Patz. At least one took notes and shared them during conversations with prosecutors when the jury had been excused. The former juror told the person she made notes when it appeared the second jury was confused, and offered suggestions on what needed to be made clearer.

ProPublica discovered that at least four of the members of the first jury are now Facebook friends with Joel Seidemann, a Manhattan assistant district attorney who helped lead the prosecution.

ProPublica asked the district attorney’s office about their knowledge of Seidemann’s social media relationship with the jurors. Again, a spokeswoman declined to comment.

Contacted over the weekend, several legal ethics experts told ProPublica that there is nothing wrong with Seidemann being friends with the jurors, so long as that friendship began after the close of the first trial.

Reached by phone, Seidemann declined to respond to questions for this story.

“It’s not a good time,” he said.

Fishbein said he was eager to explore not only how many jurors might have known about the members of the first jury in the courtroom, but how that might have affected their consideration of the case and the evidence. Fishbein said the initial vote taken by the second jury broke down almost evenly, with seven favoring conviction and five acquittal. He said his concern is that the presence of the former jurors — particularly their support and accompaniment of Stan Patz — might have influenced their verdict in a highly emotional case.

He said he was especially concerned because Castellon, the juror who disclosed the court officer’s role in informing the jury, “was outspoken regarding the guilty verdict at the press conference.”

Nate Schweber contributed reporting to this story.