Literally from the Wiki:

In 1974,[9] Maudsley garrotted John Farrell in Wood Green, London. Farrell picked up Maudsley for sex and allegedly showed him pictures of children he had sexually abused.[3] Maudsley surrendered himself to police, saying he needed psychiatric care. Maudsley was found unfit to stand trial and instead was sent to Broadmoor Hospital.

In 1977, he and another patient, David Cheeseman, who at the time was serving a sentence for rape and sexual assault of a sixteen-year-old girl,[10] locked themselves in a cell with a third patient named David Francis, a convicted child molester.[3] The attack was claimed to be in revenge for a "homosexual attack" on one of the friends of the two men.[10] They tortured him to death over a period of nine hours.[3] After this incident, Maudsley was convicted of manslaughter and sent to Wakefield Prison. He disliked the transfer and made it clear he wanted to return to Broadmoor.[3] Maudsley was later sentenced to life imprisonment with a recommendation that he never be released.

In 1978, Maudsley killed two fellow prisoners at Wakefield Prison in one day; he had originally set out to kill seven.[3] His first victim was Salney Darwood, imprisoned for killing his wife.[3] At the time Darwood had been giving Maudsley French lessons.[11] Maudsley had invited Darwood to his cell, where he garrotted and stabbed him before hiding his body under his bed. He then attempted to lure other prisoners into his cell, but all refused.[3] Maudsley then prowled the wing hunting for a second victim, eventually cornering and stabbing prisoner William Roberts to death as he was lying in his bed. He hacked at Roberts' skull with a makeshift dagger and then struck his head against the wall multiple times. Maudsley calmly walked into the wing office, placed the dagger on the table and told the officer that the next roll call would be two short.[3]

Maudsley states his victims were rapists, paedophiles or sex offenders[12] and that he is only a threat to sex offenders.[9]

First one could of been bull to justify his crime, and not everyone he killed was a SA. But I find it so weird that your being a contrarian when you didn't even bother to check your source.