A week after his father was found dead in a park in the suburbs of Melbourne, Mark Holcomb was left wondering why he couldn’t help.

It was a Saturday afternoon, and the 22-year-old had just finished taking a shower in his room, when he heard a knock at the door.

He opened it, and a friend and colleague were waiting for him.

“My heart stopped, and I just knew something was wrong,” Mr Holcomb said.

His father, Mark Harrison, was found slumped over his kitchen table in the backyard of his house in the Melbourne suburb of Glenelg in the early hours of Saturday, May 5, 2016.

Mr Holcomb says the death of his father left him devastated, and was particularly hard to watch.

In recent months, Mr Harrison had been a regular visitor to the Glenelgs house, often taking his mother and brother to visit.

He was a keen cyclist, and Mr Holcombe said he was “very keen” on the sport.

On the night he died, Mr Holcott says he was on his way home from a job interview when he received a call from the police.

The coroner said it appeared Mr Harrison died from an accidental overdose, and that the drugs found in his system were heroin.

Investigators were now looking into whether the drugs were laced with fentanyl, a powerful opioid that has caused several fatal overdoses in recent months.

When Mr Harrison went missing from his Glenelgins home, he had been reported missing to police by his mother, but police did not take action, according to local media reports.

Police say Mr Holcpbs death was a tragic accident, but that his father had been involved in a long-running drug and alcohol problem.

‘Weird’ to be found dead at his home, friends say Mark Holcombe was shocked to find out he had lost his father.

But it was hard not to wonder if Mr Harrison was being paid off by a drug dealer or the drugs he was taking were laced.

Mark Harrison, 22, died in a car accident after he was stopped for driving while impaired by drugs in the southern suburbs of Victoria in April 2016.

His body was found at a petrol station in Glenelgin, near Melbourne, on Sunday.

As his body was removed from the car, Mark’s father, a successful cyclist, cried and held the back of his head.

Mason County Coroner Bruce Hall said it was a “tremendous shock” to discover Mr Harrison’s body at the Glenels house, and his family were devastated.

A neighbour, Chris Pynn, said the young man was a good man, who was “a very caring person”.

“He was very nice to everyone,” Mr Pyns told ABC Melbourne.

Calls for an investigation Mark Harrison had not been seen by police for a week and had not returned home.

It’s believed Mr Harrison, who lived in Glenels Glen, south of Melbourne’s CBD, had been working on a project that involved him building a house in his father’s backyard.

At the time, he was also planning to take his son to a sports day at the local park.

Earlier on Saturday, Mr Harris’ body was pulled from the road.

Investigation into his death is still underway, and coronial police say they will take evidence from Mr HolcPs car.

Topics:law-crime-and-justice,police,drug-offences,drugs-and/or-substance-abuse,drug,glenelg-3051,melbourne-3000,vicsource ABC News (AUS)