One of the most notorious figures in the Boston clergy sex abuse scandal has completed his prison sentence on child rape charges and will be released this week after two experts hired by prosecutors found he does not meet the legal criteria to be held as a sexually dangerous person.

Paul Shanley was known in the 1960s and '70s for being a hip street priest who reached out to troubled youths. But in 2005 he was convicted of repeatedly raping and fondling a boy at a suburban parish in the 1980s, and he was sentenced to 12 to 15 years in prison.

Middlesex District Attorney Marian Ryan said Tuesday that her office hired two psychiatric experts to evaluate Shanley, now 86 years old, to see if he should continue to be held after completing his sentence. Both experts told prosecutors that he does not meet the legal criteria for civil confinement as a sexually dangerous person.

Once Shanley is released Friday, he will begin 10 years of supervised probation.

Shanley was defrocked after dozens of men came forward and said he had molested them when they were children.

Attorney Mitchell Garabedian, who represented some of those men in lawsuits against the Archdiocese of Boston, said his clients are upset that Shanley is getting out of prison.

"Unfortunately, there is no mechanism in place which will prevent Paul Shanley from sexually abusing once again," Garabedian said. "When it comes to a sexual abuser abusing an innocent child, the abuser can be 35 or 95 — there's no age limit."

Ryan said Shanley is prohibited from interacting with children.

"The defendant will be monitored by the probation department for the next 10 years and has been ordered to have no contact with children under 16 years of age," she said.

Under a Massachusetts law, prosecutors may petition a court to have a defendant indefinitely confined as a sexually dangerous person after completion of a prison sentence if the state can prove he suffers from a mental illness or abnormality that makes him incapable of controlling sexually dangerous impulses.

After Shanley was convicted, prosecutors asked a judge to send him to prison for the rest of his life.

Ryan said both doctors who evaluated Shanley concluded that he does not satisfy the legal criteria for prosecutors to file a petition seeking to confine him after his prison sentence.

During the trial, Shanley's accuser, then a 27-year-old firefighter, said Shanley would pull him from Sunday catechism classes and rape and fondle him at St. Jean's parish in Newton, beginning when he was 6 years old. The man said he recovered memories of the abuse as the clergy sex abuse scandal unfolded in the Archdiocese of Boston during the early 2000s.

Shanley's trial attorney, Frank Mondano, declined to comment on Shanley's upcoming release from prison. During the trial, Mondano challenged the reliability of the accuser's repressed memories.

Shanley's appellate lawyer, Robert Shaw Jr., said Shanley has "served his time."

"We've never believed that he was dangerous, and we didn't believe that what he was convicted of was a valid conviction, given that it rested on repressed memory evidence that we did not believe was valid," he said.

The Archdiocese of Boston, the fourth-largest archdiocese in the country, with more than 1.8 million Catholics, said Shanley's crimes against children were "reprehensible."

"No young person should ever have to experience such violations of their safety and dignity," it said in a statement released Tuesday.

The clergy sex abuse scandal exploded in Boston in 2002 after a series of stories by The Boston Globe revealed that dozens of priests in the archdiocese had molested and raped children for decades while church supervisors covered it up and shuffled abusive priests from parish to parish. Thousands of victims came forward in Boston and around the world, describing sexual abuse by priests that dated back decades.