CONCORD, N.H. – A New Hampshire man serving a life sentence for killing a woman and maiming her daughter in a 2009 home invasion has been injured in a prison fight.

WMUR-TV reported that since going to state prison in 2011, Christopher Gribble has been in a special housing unit where he has had no contact with other inmates. Last week, he was moved to a unit where he has a cellmate and can interact with inmates.

The fight took place on Oct. 13 in the recreation yard and involved at least one other inmate. Gribble was treated for minor facial injuries. The prison is investigating.

Inmates in the closed custody unit are locked down about 20 hours a day and can leave the unit to go to the dining hall and get contact visits. They can interact with other inmates in the recreation yard on a limited basis.

Gribble and Steven Spader were convicted of the machete and knife attack that killed Kimberly Cates and severely injured her daughter, Jaimie, in Mont Vernon. They were sentenced to life. Three others were sentenced to lesser crimes.

Gribble took the stand in his own defense during the 11-day trial, claiming he had been abused by his mother and that he had fantasized about torturing and killing her. He asked a jury to find him not guilty by reason of insanity. Prosecution experts who examined him testified that he had an anti-social personality, but was not insane.

Gribble testified he felt nothing as he plunged the knife into Cates’s throat and tried to kill Jaimie. He said he felt a flood of relief after the attacks.

Soon after the jury returned the verdict against Gribble, Judge Gillian Abramson told him “infinity is not enough jail time.”