A prison security video showing guards struggling to enter a cell where a convicted killer was strangling a defrocked pedophile priest has turned up on the Internet.

State prison officials were investigating how the 10-minute video, shot from outside former Roman Catholic priest John Geoghan's cell during his slaying, made it onto YouTube.

The video was posted last month and may have been brought to the Boston Herald's attention by Joseph Druce, who was convicted in January of killing Geoghan at the Souza-Baranowski maximum security prison in August 2003.

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"The truth about officer involvement in John Geogan's (sic) death," a handwritten note sent to the Herald and signed "Joseph Lee Druce" says.

The note gives a link to the video and the message "The truth about officers allowing J.G. to die through their neglect. Let the truth be know (sic)."

The video shows up to five guards at a time tugging at the door Druce had wedged shut with a book, while other guards stand ready to enter the cell.

About halfway through it, guards pry the door open, and several rush into the cell before emerging seconds later dragging someone out, presumably Druce, and pinning him to the floor. What appears to be medical personnel then rush into the cell. Viewers can neither see the slaying in progress nor Geoghan's body.

Worcester County District Attorney Joseph Early Jr. said Friday that several copies of the video were distributed after Geoghan's death, including to the district attorney's office and Druce's lawyer. Early said he was not sure whether the video was the same one shown during Druce's trial.

"We don't know at this point where it came from, and we're looking into how we can get it removed from the site right away," he said. "It was a horrific crime, and this desensitizes and glorifies that violence."

Inmates do not have access to the Internet and state Department of Correction officials were investigating how Druce may have obtained it, department spokeswoman Diane Wiffin said.

"We have no idea where he got it from. We don't know where the tape came from or how it got on the Internet," Wiffin told the Herald on Thursday night.

The president of the guards union said the state should "immediately use any legal remedy available" to get the video off the Web. It was still accessible Friday morning.

"We are deeply concerned that an internal security video was posted by an inmate or an inmate's family," said Steve Kenneway, president of the Massachusetts Correction Officers Federated Union. "It's absolutely a public safety issue, posting emergency response actions of correction officers on the Web."

Druce was already serving a life sentence for murder when he killed Geoghan.

Geoghan, 68, was serving a nine- to 10-year sentence for groping a 10-year-old boy, but had been accused of molesting as many as 150 boys. His case helped spark the clergy sex abuse scandal worldwide after church personnel records released under court order revealed that the Boston Archdiocese transferred Geoghan from parish to parish even after allegations of abuse surfaced.

Druce claimed he was chosen by God to kill pedophiles and unsuccessfully used an insanity defense at his trial.

In August 2005, the Herald obtained a video that showed Druce re-enacting the slaying in which he strangled Geoghan with a pair of socks. Druce then climbed on his cot and jumped off repeatedly to show how he crushed convicted molester's body.