John Leslie Coombes was born on September 14, 1954, in Victoria, Australia.

In 1984, John Leslie Coombes committed his first murder by stabbing Henry Desmond Kells, a 44-year-old man, at Kells' home in Chelsea. Coombes was sentenced to life imprisonment in December 1985, but his sentence was later reduced to a minimum of 11 years.

Seven weeks after his release in 1996, Coombes was charged with the murder of Michael Peter Speirani. Speirani had gone missing while on a fishing trip. His body was found stabbed and mutilated, dumped a few kilometers off the coast of Port Phillip Bay. In 1998, Coombes received a 10-year minimum sentence for this crime. He was paroled in 2007.

In August 2009, Coombes murdered Raechel Betts, a 27-year-old childcare worker. This crime took place at the home of his co-defendant, Nicole Godfrey, on Phillip Island. After strangling Betts, Coombes dismembered her body in a bathtub and disposed of the parts off a pier at Newhaven. During pre-trial proceedings at the Supreme Court, he changed his plea to guilty. He was sentenced to life imprisonment with no chance of parole.