The man convicted of strangling a defrocked pedophile priest in a Massachusetts prison says three guards dragged him out of his cell and beat him on Halloween night.

Department of Correction spokeswoman Diane Wiffin says the alleged incident at MCI-Cedar Junction in Walpole is under investigation.

Leslie Walker, director of Massachusetts Correctional Legal Services, a prisoners' rights group, tells the Boston Herald that Joseph Druce was "very badly bruised." Her group is also investigating Druce's claims.

Druce was already serving a life sentence for murder when he killed former Roman Catholic priest John Geoghan in his cell in August 2003. Druce claimed God told him to kill pedophiles.