Police say three teenagers murdered man in 'carjacking gone wrong'

Paul Costa was the father of four children.
Paul Costa was the father of four children.

Police will allege three teenagers murdered Paul Costa, whose family run a Christmas tree business at Napoleons, in a Melbourne reserve in a carjacking gone wrong.

His body, clad in an Ermenegildo Zegna suit, was found by a passer-by in Dunstan Reserve, a popular dog walking spot and sporting ground at Brunswick West, just after 8.20am on July 3.

Homicide squad detectives arrested a 17-year-old boy and an 18-year-old man in Thomastown on Thursday morning.

A 16-year-old was arrested in the NSW city of Newcastle and will be extradited to Victoria on Friday. 

All three have been charged with one count of murder. 

It is understood detectives will allege Mr Costa, a 43-year-old father, was killed in a botched carjacking.

Prosecutors allege Mr Costa was murdered on July 2, one day before his body was found.

The 17-year-old appeared in a Children's Court late on Thursday afternoon, charged with murder.

Police search a park near where Paul Costa's car was found.

Police search a park near where Paul Costa's car was found.

Police are still analysing CCTV footage and some mobile phones have been seized which could yield more clues, Prosecutor Ashleigh Harrold said.

"It was a very complex scene, I'm instructed."

The 18-year-old faced Melbourne Magistrates Court on Thursday afternoon, charged with murder.

The man's identity was suppressed, during the brief court hearing.

The court heard he was vulnerable in custody due to his young age, and that he had limited cognitive abilities and functions.

There was no application for bail and the man was remanded in custody until a committal mention hearing, on January 15 next year.

Mr Costa's family sat at the back of the court for the hearing, behind the 18-year-old's relatives.

He was last seen by his parents the night before his body was found, leaving the house in his suit and best dress suit.

His father, Alex Costa, who farmed Christmas trees at Napoleons for almost 30 years, thought he was going on a date. 

The older Mr Costa said at the time that the youngest of his four children, who was a father of four himself, was a gentle giant.

"He would never hurt anyone; he would not even hurt a bird," he said.

The dead man's car, a red Nissan Patrol, was discovered four days after his body was found, about three kilometres away in Berry Street, Coburg.

It had been abandoned a little over a kilometre from the home Mr Costa shared with his parents.

Melbourne had been in the grips of a carjacking crime wave with the crime doubling in the five years to 2016.

The most recent figures from the Crime Statistics Agency show there had been 32 carjackings – or eight a month – from December 2016 to March this year and 13 attempted carjackings. 

Anyone with information is urged to contact Crime Stoppers on 1800 333 000 or make a confidential report at www.crimestoppersvic.com.au

With AAP