A former police officer has refuted serial killer Ivan Milat's claims he was framed for his crimes.
Retired NSW Police senior investigator Shaun Roach worked on the case of the Belanglo State Forest backpacker murders, as a member of the forensic ballistics section.
Mr Roach's department was involved with the post mortems of skeletal remains, the excavation and examination of the crime scenes and eventually the trial of Milat at the NSW Supreme Court.
Milat wrote a letter to The Sun-Herald in July this year, in which he claimed he was framed for the murders of seven backpackers at Belanglo State Forest in the 1990s.
Mr Roach dismissed the claims.
"It comes as no surprise to me, as I'm sure it comes as no surprise to anyone that was involved with [the case], that he's adopted this position and maintained his innocence all the way through," he said.
"Ivan hasn't admitted to breathing basically.
"He's been extremely unhelpful. We always suspected he would be unhelpful, and moving forward into the future he would be resistant to any suggestion he had any involvement with any of these matters.
Throughout his time working on the case, Mr Roach found himself in close proximity to Milat on several occasions.
"He was very contained, around police quite compliant, polite to a certain extent," he said.
"I never saw him angry or really upset in the time that I was around him.
"I don't know how you'd describe him, just contained and controlled in his demeanour but an interesting character. I'm certain that he's not mad, just a bad individual, a bad person."
Between 1989 and 1992 seven backpackers disappeared as they hitch-hiked down the Hume Highway.
Their bodies were eventually discovered in various locations near fire trails in the Belanglo State Forest, covered in sticks and ferns.
Several backpackers were shot in the head, while one was decapitated. Some body parts have never been found.
Just over four years later, Milat was found guilty of all seven murders.
Milat received more than seven life sentences for the crimes.
Mr Roach assisted the investigating detectives with exhibit handling, almost on a daily basis throughout Milat's trial.
The former senior investigator was also present when the jury handed down its verdict.
He sat next to the families of the deceased backpackers, who were elated with the result.
"It was a very emotional time when those seven guilty verdicts were handed down," Mr Roach said.
"You're sitting there in the gallery among still quite raw and grieving relatives, who are beside themselves with joy that justice has been done for their loved ones. There were a lot of tears and a lot of hugs.
"It was a very emotional time but I was very honoured to be there at that time."
Milat is currently in the medical ward of Long Bay gaol, undergoing chemotherapy for oesophageal cancer.