Haigh was born in 1957 in Melbourne. Between April 1978 and August 1979 he killed six people: Evelyn Abrahams, fifty-eight, and Bruno Cingolani, forty-five, shot in armed robberies of a pizza shop and a hotel; Wayne Keith Smith, twenty-seven; Sheryle Gardner, thirty-one, and her son Danny Mitchell, ten, shot because Gardner was a witness; and Lisa Brearley, nineteen, his girlfriend, who was stabbed and strangled. The killings were a mixture of robbery, dispute and the elimination of witnesses.
He was arrested in 1979, convicted, and sentenced to life. In 1991, in Pentridge prison, he killed a fellow prisoner, Donald George Hatherley, who had asked him to; Haigh maintained it was assisted suicide and was convicted of murder. He received a further life sentence.
He has six sentences of life imprisonment without the possibility of parole. He is one of a small number of prisoners in Victoria formally never to be released, and he has litigated repeatedly over conditions and over access to material about his own case.
The Brearley and Hatherley killings are what make the case unusual, and both were disputed by him in different directions: he denied intent in the first and claimed consent in the second. Neither account was accepted.