Peter McNeill had tried to pull his young son Dane out of a downward spiral the world of illegal drugs.
"In the last couple of months he just really went downhill and unfortunately got mixed up in the wrong crowd," Mr McNeill said at his Narellan home on Sydney's southwest fringe.
"He didn't really tell us anything about them.
"We were forever trying to help him but he just made his own choices."
When Dane did not come home last weekend, Mr McNeill was worried but thought he was just off with his mates.
The last sighting of the 20-year-old alive was on Friday afternoon at a McDonald's in Casula in Sydney's southwest.
On Sunday afternoon, Mr McNeill and Dane's mother, Rebecca, reported him missing.
Less than 24 hours later, a council worker opened the gates to the Lambeth Street Reserve at Picnic Point and found Dane's badly burnt body on a roadway.
The death came just a month after Dane pleaded guilty to a string of drug charges in Campbelltown Local Court.
In May, on two separate occasions, police found him high on the drug ice the middle of the night in St Andrews.
On one occasion, he had a padlocked bag with scales, a drug tick book, ice and ecstasy.
His girlfriend of more than 18 months, Jade Patterson, was in the front seat when police pulled their car over on May 20.
She had $605 in cash with her, court documents state.
Dane was due to be sentenced next week.
Mr McNeill said Jade and Dane were "it together but obviously she didn't know about some of the stuff he was doing and what got him into trouble", he said.
Detectives turned up at Ms Patterson's home on Thursday.
She was too distraught to speak to the media.
After police charged Dane with drug offences in May, he underwent counselling.
However, his family fear his links to the drug world culminated in his horrific death.
Despite Dane's struggles with addiction and his naive attempts to keep his parents at arm's length, Mr McNeill remembered him as a beautiful boy.
He said Dane and his younger brother, Ryan, were particularly close.
"They were each other's heroes," Mr McNeill said.
Homicide detectives are attempting to retrace Dane's final footsteps and are investigating whether he was killed elsewhere and his body was dumped at Picnic Point.