NEW BEDFORD — George Perrot helped his mother down the steep courtroom stairs Wednesday and stepped outside, light snow landing on his shaven head.

After an almost 30-year ordeal in prison, he was free. Superior Court Judge Robert Kane, in a dramatic court hearing minutes earlier, said plainly that he believed Perrot was innocent of 1985 rape charges that landed him a life sentence.

Kane freed Parrot on his own recognizance after his 1992 rape conviction, which was based largely on the now-discredited science of microscopic hair analysis, was overturned last month in what may prove to be a landmark ruling.

The record, Kane said during an impassioned decision delivered from the bench, “makes me reasonably certain that George Perrot did not commit those grave offenses.’’ As Kane spoke, Perrot wiped at his eyes and nose, dabbing his face with the prison jumpsuit he’s donned for much of three decades. Released without bail, he leapt up and hugged the lawyers who argued his case free of charge.

“Let’s get those shackles off you,’’ a bailiff said, leading Perrot back behind the courtroom for what Perrot promised his mother was the last time.

“She told me I better not go back in there,’’ said Perrot when asked what he and his mother had whispered to each other as they embraced. He said there was a steak dinner in his future.

“I love him. I’m so happy he’s coming home,’’ said Perrot’s mother, Beverly Garrant.

Arrested in 1985 for the rape of a 78-year-old neighbor in Springfield, Perrot was convicted in 1987 largely on the analysis of a single hair found at the scene. The guilty verdict was thrown out because the trial included evidence that was later ruled inadmissable. But he was convicted again in 1992.

Even the prosecution’s filings appeared to point Kane toward the decision to free Perrot. A prosecution document filed Tuesday, he said, seemed to support the defense’s case.

During the hearing, Kane gave the document to Kirsten Mayer, a lawyer from Ropes & Gray who has been among several representing Perrot. The Committee for Public Counsel Services Innocence Program and the Schuster Institute for Investigative Journalism at Brandeis University also had taken up Perrot’s case.

As Mayer read the document at the defense table — new information from a late-1980s psychiatric evaluation of Perrot that prosecutors had withheld, she said later — she began to weep.

Through tears, she told Kane she couldn’t understand how prosecutors could have continued to pursue the charges against Perrot.

“It not only contradicted what the Commonwealth had submitted to us yesterday, but showed,’’ Mayer said, “that Mr. Perrot even as a teenager facing the rest of his life in prison was taking responsibility for his alcohol and drug issues and was denying that he had any part in the rape of the victim.’’

Mayer declined to comment on whether the prosecution had acted unethically in withholding the information.

“It’s over and done with,’’ said Mayer. She said Perrot’s lawyers felt privileged to have the chance to help right a major injustice.

The victim, now deceased, never identified Perrot as her assailant. The man who attacked her was clean shaven, she insisted; Perrot had a beard.

But he did have wavy brown hair then. An FBI analyst testified that the hair found at the scene was Perrot’s.

At the time, the testimony was compelling, but since then the science behind hair analysis has been largely debunked as unreliable. More cases that relied on that science could soon be overturned, experts said.

In addition to the hair analysis, the case against Perrot leaned heavily on a confession that Perrot gave to police. His lawyers argued the confession was made during an intense 12-hour interrogation, conducted with no parent or lawyer present, during which he was incoherent and high on drugs. And prosecutor Francis W. Bloom, Kane wrote, despised Perrot.

It’s unclear whether Hampden County prosecutors, who argued Wednesday that Perrot should be held without bail, will seek to try him again. Prosecutors waited to emerge from the courtroom until Perrot did, leaving amid the scrum surrounding the newly free man.

In arguing to hold Perrot without bail, Hampden County Assistant District Attorney Elizabeth Dunphy Farris pointed to three escape attempts on Perrot’s incarceration record and an extensive disciplinary history behind bars. He’d also fled to Maine briefly after his second conviction was reversed — a decision that also was short-lived as his conviction was soon reinstated by a higher court. And though the rape conviction was overturned, a burglary conviction that Dunphy Farris called “equally disturbing to the elderly victim’’ had been upheld.

But in court on Wednesday, Kane said Perrot’s jailhouse infractions appeared to be the result of prison culture and what Perrot himself once described as deep resentment over serving a life sentence for a crime he did not commit.

For Perrot, life is just beginning. He has a place to live and a job waiting for him, working on properties for an real estate investment company. But freedom after incarceration has its own hardships, and before setting him free, Kane wished Perrot luck.

He declined to order a GPS tracking bracelet that would serve as constant reminder of how prison had hobbled Perrot for three decades, even though the defense had agreed to that condition.

“I know from experience that people we call criminals can break out of expectations for a variety of reasons,’’ Kane said, pointing to the support network of friends, family, and advisers whom Perrot has found in recent years.

“Ultimately, it will be up to George Perrot,’’ said Kane.

Kane then took the unusual step of issuing an oath to Perrot himself.

“Do you swear to this court that you will honor the terms of personal recognizance?’’ Kane asked.

“I do, your honor,’’ Perrot said.

Mayer said that was especially meaningful.

“He’s telling Mr. Perrot that he believes he will keep his word,’’ Mayer said. “For someone who has been in prison for 30 years, who has been disbelieved every time he denied this crime for 30 years, that is one of the most beautiful gifts that the court can give.’’

Nestor Ramos can be reached at nestor.ramos@globe.com. Follow him on Twitter @NestorARamos