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.
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