WORCESTER, Mass. (AP) – An inmate accused of killing notorious pedophile John Geoghan spent weeks plotting the slaying, doctoring a book to jam shut a cell door and stretching out socks he tied around the defrocked priest’s neck, a prosecutor said Monday.

“He looked upon Father Geoghan as a prize,” Worcester District Attorney John J. Conte said. “No question he had been planning it for well over a month.”

The suspect, Joseph L. Druce, and Geoghan had just finished lunch in their cells and were let out to return their trays when Druce followed Geoghan into his cell about 11:52 Saturday morning, before the doors were locked again.

In the upper track of the cell door, Druce jammed a book from which he’d torn out some pages to fit the slot, then put nail clippers and a tooth brush in the door’s lower track to prevent guards from opening it.

He tied Geoghan’s hands behind his back with a T-shirt, then used the stretched-out socks, a pillow case and one of Geoghan’s shoes to strangle him, Conte said. Druce didn’t use a razor he had with him, but may have intended to castrate the former priest, Conte said.

A fellow prisoner saw the assault and conferred with another inmate before telling a guard, Conte said. The guard couldn’t open the cell door because it was jammed. By the time help arrived to open the door and a nurse came to treat Geoghan, seven or eight minutes had passed, Conte said.

Conte said Druce, who has been cooperating with investigators, told investigators he planned the attack for over a month. Druce is believed to have acted alone.

The 68-year-old former priest – who came to symbolize the widespread sex abuse scandal in the Roman Catholic church – was taken to Leominster Hospital, where he was pronounced dead at 1:17 p.m. An autopsy Monday showed that Geoghan died from strangulation and blunt chest trauma. He also had broken ribs and a punctured lung, Conte said.

Druce was in Cell 21, while Geoghan was in Cell 2. Conte said part of an investigation being conducted by his office, state police and the Department of Correction would try to determine how many cells should be opened at any one time on the protective-custody block and whether there is enough staffing at the prison.

Druce is serving a life term at the maximum security Souza-Baranowski Correctional Center in Shirley for killing a gay man 15 years ago.

“He has a long-standing phobia, it appears, towards homosexuals of any kind,” Conte said. “I’m not a psychologist and I’m not a psychiatrist, but I would say he’s filled with long-standing hate.”

Geoghan allegedly molested nearly 150 boys over three decades and became a catalyst for the clergy sex abuse scandal in the Catholic church. He was serving a nine- to 10-year sentence for assault and battery on a 10-year-old boy. He’d been in protective custody since being transferred to Souza-Baranowski in April, officials said.

Gov. Mitt Romney on Monday appointed a panel headed by state police Maj. Mark Delaney, to conduct an independent investigation.

“Right now we are going to do a thorough review and re-evaluate all of our policies and procedures,” state Public Safety Secretary Ed Flynn said. “We cannot escape the fact that an inmate died while in the care of the Department of Correction.”

Flynn said surveillance cameras filming the protective custody unit while the attack took place are being reviewed.

Druce, 37, a reputed member of the neo-Nazi group Aryan Nation, was convicted in the June 1988 murder of George Rollo, a 51-year-old gay bus driver who had picked Druce up hitchhiking. Druce, who then went by his birth name, Darrin E. Smiledge, attacked Rollo, stuffed him in the trunk of Rollo’s car, drove him to a wooded area and strangled him, according to court documents.

Smiledge attacked the bus driver when Rollo made a sexual advance, the documents say.

An insanity defense failed and Smiledge was sentenced to life in prison.

Smiledge also pleaded guilty to sending fake anthrax from prison to lawyers with Jewish-sounding names and was sentenced to an additional 37 months in prison.

Conte has said Druce will be charged with murder once a grand jury is convened in September. Druce remains in isolation in the prison.

Geoghan’s abuses cut a wide swath through parishes in the Boston Archdiocese – and he came to symbolize the horrors of pedophile priests and the exhaustive steps church hierarchy would take to keep the allegations under wraps.

Geoghan was ordained in 1962, starting a 34-year career that took him to six different parishes. Along the way, he left behind a trail of allegations of predatory abuse.

“Geoghan personified the pedophile priest,” said Jim Post, president of Voice of The Faithful, a lay reform group formed in the wake of the abuse scandal.

In January 2002, a judge presiding over lawsuits against Geoghan ordered the release of internal church documents, which showed that Geoghan continually had been allowed to return to pastoral service, despite mounting evidence of compulsive pedophilia.

Geoghan was granted early retirement in 1996 and praised for an “effective life of ministry, sadly impaired by illness” by Law, who ultimately resigned in December 2002 for his role in the scandal.

With legal troubles mounting, Geoghan was defrocked in 1998, and in December 1999 charged with raping and molesting three boys. The archdiocese eventually settled with 86 Geoghan victims for $10 million.

AP-ES-08-25-03 1755EDT