Homicide Squad detectives said 18-year-old St Albans man Hieu Nguyen, who was killed in May last year, was known to police for drug-related offending.

Mr Nguyen was stabbed to death. His body was found on the nature strip outside the hospital in Majorca Street, St Albans about 5.30am on May 11.

He is related to Tim Nguyen, who died after being accidentally shot in the chest by a friend who was showing off his sawn-off shotgun. Tim Nguyen was dumped outside the same hospital in 2008, but police say the killing is not linked.

Detective Inspector John Potter said a man seen driving erratically in a Honda Civic that was later found burnt out is a suspect in the murder.

A witness told police they saw the car being driven erratically by a man with dark coloured hair along the Keilor-Melton Highway near the intersection of Kings Road in Taylors Lakes about 8am that morning.

The car was found burnt out on Leakes Road in Plumpton, about 10 kilometres away, later that morning.

The man, who is known to police, had been lent the car while the owner was overseas.

"We have suspects in this case but it's important for us to establish exactly what happened that day regarding that car," Inspector Potter said.

"We think the car is the link to the whole thing

“It's important for us and for Mr Nguyen's family to find out what happened to him that day."

He would not comment on Mr Nguyen's previous offending, but said it was possible drugs were in some way linked to the death. He said it did not appear Mr Nguyen was tortured.

Detectives believe Mr Nguyen was stabbed at another address before he was taken in a car to the hospital. Security camera footage from the hospital has not assisted police.

nbucci@fairfaxmedia.com.au