A late Manhattan pediatrician molested countless young patients over the course of decades, an investigation into his conduct has concluded.

Dr. Reginald Archibald, who died in 2007, worked at Manhattan’s Rockefeller University Hospital as an endocrinologist specializing in child growth from 1948 to 1982.

After being inundated with complaints from former patients — many now elderly or deceased — the hospital commissioned the law firm of Debevoise & Plimpton to probe the mountain of disturbing allegations last year.

The report, released Thursday, confirmed the doctor’s decades-long reign of predatory abuse.

“It is clear that Archibald, taking advantage of his position as a trusted and respected physician and researcher, engaged in a widespread pattern of misconduct and sexually abused many children at the Hospital over the course of many years when offering patients medical care and treatment,” the report found.

The probe noted that Archibald saw many patients who reported no misconduct — but still argued that he should have been probed with far more urgency as the whispers around him increased.

“With the benefit of hindsight, however, and viewed in light of today’s greater knowledge of sexual abuse and current standards of appropriate practices and procedures for studies and treatment of children, there were warning signs that could have been seen, appreciated or further pursued earlier,” the report states.

Attorney Jennifer Freeman, who is representing 150 of his accusers, has called Archibald “the most prolific pedophile in U.S. history.”

The report revealed that suspicions stretched back decades.

“It’s horrific evidence that they knew about it in 1960,” Freeman said, referring to an abortive investigation that year. “The president knew about the investigation. What did he do with that knowledge? Apparently nothing.”

Another attorney for the victims, Jeffrey Herman, echoed that charge.

“This is Jerry Sandusky all over again,” said Herman, referring to the ex-Penn State football coach whose rape and sexual assault of boys continued despite warning signs.

In addition to photographing countless children naked, Archibald masturbated patients under the pretext of drawing semen samples for research purposes, according to the report.

He also routinely fondled children he examined and would even brush his face against their genitals.

One of the victims Freeman represents, Mitchell Scher, said he was happy with the formal recognition of Archibald’s abuse – but wished his tormenter was still around to suffer the consequences.

“I’m glad this is finally coming out,” Scher told The Post. “Unfortunately, no one is going to go to jail for this. This was a major cover up by the hospital.”

Archibald escaped any serious vetting during his life due largely to his sterling reputation and the inherently sensitive nature of his research.

But the report was conclusive in its findings, asserting that his methods were far from benign.

“Much of Archibald’s behavior must be seen as motivated by improper sexual interests,” the report said.

Under mounting pressure, Rockefeller commissioned an investigation in 2018 that included interviews with more than 1,000 former patients and colleagues.

Many of Archibald’s victims expressed concerns that their exploitative photographs might still be in existence or even digitized.

But the report suggested that Archibald likely destroyed the images in his possession.

Rockefeller University Hospital said in a statement Thursday, “We profoundly apologize to those patients who experienced pain and sufferings a result of Dr. Archibald’s reprehensible conduct.”