Defrocked pedophile priest John Geoghan (search) never should have been moved to the dangerous-inmate unit where he was strangled and beaten to death by another prisoner last year, according to an investigative report released Tuesday.

A series of "overzealous and unwarranted" discipline reports by a handful of guards led to the frail, 68-year-old Geoghan being classified as one of the state's most dangerous prisoners, and landed him in a cell unit with murderer Joseph Druce (search), investigators found.

The investigation, conducted by a three-member commission appointed by Gov. Mitt Romney, found that failures in the inmate classification system, disciplinary procedures and internal investigative practices by the Department of Correction all contributed to the circumstances that led to Geoghan's slaying Aug. 23.

Geoghan, the priest at the center of the Boston Archdiocese's clergy sex abuse scandal, was killed at the maximum-security Souza-Baranowski Correctional Center (search) as he and other inmates returned to their cells after lunch.

Druce, who was serving a life sentence for killing a gay man, is charged with murder.

Authorities said Druce followed Geoghan into his cell, then jammed the door shut as he beat and strangled Geoghan.

The investigative report, more than 100 pages long, details numerous problems that led to Geoghan's killing.

"It's absolutely shown in this report that under no circumstances should John Geoghan have been in the special housing unit at Souza-Baranowski Corrections facility," state Public Safety Secretary Edward Flynn told The Associated Press.

The report did find that Druce worked "alone and in secret," and that there was no evidence anyone at the prison — inmate or employee — knew of his plans to harm Geoghan.

While the report cites specific failures at Souza-Baranowski that allowed Geoghan to be attacked — including insufficient staffing procedures at his unit — much of the criticism focuses on his time at MCI-Concord, the medium-security prison where he was "unduly harassed and physically abused," the report said.

Specifically, the report cites trivial infractions written up as disciplinary reports against Geoghan by guards at MCI-Concord, where Geoghan was housed until five months before his death. The disciplinary reports helped spur a decision by prison officials to increase Geoghan's "dangerousness" classification and transfer him to the maximum-security prison.