Damien Noyes, then six, had been playing with his brothers in a park across the road from his Whalan home, just 15 minutes outside of Penrith in Sydney's west.
The boy was then kidnapped by Lett after inviting him to go for a drive.
Noyes was driven to Penrith Railway Station where he told the man he wanted to go home before punching him.
Lett, who had been drinking all afternoon, then strangled the young boy with his underpants and shorts before he threw him out of the vehicle and then ran over his body multiple times.
His naked and broken body was found dumped in the carpark the following morning. His underwear was still tied around his neck.
A post-mortem examination found Noyes had drowned in his own blood due to strangulation and injuries to his face.
The boy had also suffered several broken bones including his leg, ribs and jaw and was left with tyre marks across his bare belly.
During the murder trial, Lett's crime was described as horrific, cruel, callous, cold-blooded, senseless and tragic by the Crown prosecutor.
Earlier this year the boy's mother Bridget Cohen spoke publicly for the first time in 25 years after it was revealed Lett would be getting released.
'I just wanted him to suffer for the rest of his life,' she said.
Of her boy, Cohen described him as an outgoing child who considered himself the man of the house.
'He wanted to be a politician or garbage truck driver,' she recalled, before admitting she still misses him terribly.
'I don't think I'll ever get over it,' she added.
Lett claimed he had abducted the boy for sexual reasons but said he couldn't go through with it. He was found guilty of murder in February, 1994.
He was later convicted of the rape of a young boy between 1988 and 1992.
Ahead of his upcoming release from prison Lett was interviewed by Forensic psychiatrist Kerri Eagle.
During the meeting Lett reportedly said that his sexual fantasies were simply not going to be a concern for him following his release.
However, Eagle has stated that he had 'unrealistic' and 'poor expectations' on how to controls his desires, adding that he may potentially be at risk of re-offending again.
It is understood that the NSW Government has applied to the Supreme Court to have a five-year supervision order including some strict conditions to prevent the convicted killer from re-offending.