Three men have been charged after an assault at Auckland Prison last week.
The Herald understands the man who was allegedly attacked was double murderer Graeme Burton.
The incident on May 11 happened at Auckland Prison in Paremoremo, north of Auckland.
Three males aged 20, 26 and 37, have been charged with wounding with intent to cause grievous bodily harm.
They were all due to appear in the North Shore District Court via AVL on June 7.
Burton shocked the country with his violent crimes.
In 1992 Burton, while under the influence of drugs and alcohol, murdered Paul Anderson after being denied entry to a Wellington nightclub.
In 2007, he gunned down father-of-two Karl Kuchenbecker while on parole.
The following year Burton was charged with stabbing another inmate.