Up until this week, Stanley Patz was preparing for another trial.

Nearly 50 years after his 6-year-old son, Etan, vanished from the streets of Manhattan, the man who had been convicted in the disappearance, Pedro Hernandez, seemed likely to return to court. He was found guilty in 2017 of kidnapping and murdering Etan, but an appeals court overturned the conviction last July.

For Mr. Patz, that meant, at 84, he would need to return to New York City from his current home in Honolulu. He might have had to move in with his older brother to attend each day of a new trial. And he would have to do it all without his wife, Julie, who died in 2020.

He worried about how, for the third time, he would spend weeks sitting in a Manhattan courtroom recalling May 25, 1979: the day Etan, carrying an elephant-print lunch bag, and walked by himself to a school bus stop down the block from their SoHo apartment.

It was his first time making the trip on his own. He never returned. Etan’s body was never found, and in 2001, he was declared legally dead.

Mr. Patz was preparing to relive that memory. Then on Monday, the Supreme Court reversed the lower court’s decision and reinstated Mr. Hernandez’s conviction.

“I am hoping that this is going to be the end,” Mr. Patz said in a rare phone interview this week. “And I will once again be able to enjoy anonymity here in Honolulu, so far away from New York City.”

Mr. Patz moved to Manhattan in 1963 and still considers himself a New Yorker. It was where he married his wife in 1965. It was where he started his family and bought an unfinished loft on Prince Street in SoHo in 1971.

But the city is also where he lost Etan.

The Patzes were in the spotlight from the moment their son disappeared. The photo of Etan grinning was prominently featured on milk cartons and plastered everywhere in the city. Etan’s family and the police desperately raced to find him.

Each anniversary, development and news cycle that placed Etan’s family back in the public eye reminded them of their loss.

“It’s something I dread,” Mr. Patz said.

When Mr. Hernandez was arrested in connection with Etan’s disappearance in 2012, more than a decade after the child was declared legally dead, Mr. Patz’s first reaction was skepticism.

Mr. Patz said he told the then Manhattan district attorney, Cyrus R. Vance Jr., “to convince me.”

“His answer was, ‘If you sit through the trial and listen to the evidence, you will be convinced,’” Mr. Patz recalled.

Mr. Hernandez, a former bodega clerk, was living in New Jersey when a relative told the authorities his suspicion that he had killed Etan.

But no scientific evidence linked Mr. Hernandez to the crime, and his confession, initially obtained after seven hours of questioning by the police, was the center of prosecutors’ case.

But Mr. Hernandez later withdrew the confession.

Mr. Hernandez’s first trial in 2015 ended with a hung jury; the lone holdout said his confession had seemed coerced.

Two years later, a Manhattan jury convicted Mr. Hernandez on the ninth day of what a jury foreman later said were “difficult” deliberations.

Since Mr. Hernandez was first charged, his lawyers have said he was wrongfully accused in Etan’s killing. They argued that the confession was made up to placate the police and that it was the result of Mr. Hernandez’s low I.Q. and the product of psychotic delusions.

In the first trial, they sought to have the confession declared inadmissible. But the judge denied their request. And several witnesses testified that they had heard Mr. Hernandez admit to killing a child in New York City, including members of his prayer group.

But his lawyers pointed to another man, Jose A. Ramos.

Mr. Ramos, who had been friends with Etan’s babysitter, was arrested and charged three years after Etan’s disappearance with trying to lure two boys into a tunnel. The police had discovered several photographs of young boys in his personal property, including one who they believed was Etan, according to reports and testimony during Mr. Hernandez’s trials.

The F.B.I. later zeroed in on Mr. Ramos. When questioned, Mr. Ramos said that he had been with Etan the day he vanished, but he denied abducting and killing him.

Federal investigators could not find witnesses to place Mr. Ramos with Etan and decided not to prosecute. In 2004, Etan’s family won a wrongful-death lawsuit against Mr. Ramos, who had refused an order to answer questions under oath about the child’s disappearance. (Mr. Ramos died in March.)

But in appeal after appeal, Mr. Hernandez’s lawyers have continued to fight to reverse his conviction. The decision last year had been their biggest success — until it was reversed after the office of Alvin L. Bragg, the current Manhattan district attorney, took the matter to the Supreme Court.

“We firmly believe he is innocent,” a defense lawyer for Mr. Hernandez, Harvey Fishbein, said. “And we firmly believe that the F.B.I. and the U.S. attorney’s office were correct when they focused on Ramos being the killer in this case.”

After observing every day of both trials, Mr. Patz, who earlier had thoughts that Mr. Ramos was the killer, said he finally felt that his family had gotten answers to what happened to his son.

He said that videos of Mr. Hernandez’s confessions were “very convincing” and were motivated by his decades of guilt over the killing. He added that he did not believe Mr. Hernandez had a low I.Q., pointing to his teaching himself English and how to play the accordion.

“Pedro Hernandez is guilty,” Mr. Patz said. “Pedro Hernandez is the man who killed Etan.”

The Supreme Court’s decision gave him a sense of relief, he said. For now.

“I hope this will never, ever, come up again,” Mr. Patz said.