The brother of man who was doused in petrol and set alight on a roadside said his family was a "train wreck" following the traumatic incident. 

The body of Shalvin Prasad was found at 6.30am last Thursday after emergency services were called to a small scrub fire on the side of McRobbie Rd in Kingseat, Auckland. 

He was burnt alive and had no other injuries.

Police today called a press conference as they piece together what happened to Prasad after he left his family home last Wednesday, then withdrew tens of thousands of dollars from ASB in Ronwood Ave, Manukau.

"This has shattered our lives and it has torn us apart, I feel like it hasn't happened and it's surreal,"  Pravin Prasad said today. 

"He was a great person and he should still be here."

Prasad, 21, lived at home with his parents, brother and sister in law. 

Police today said an accelerant, most likely petrol, was used to set Prasad alight.

Detective Inspector Dave Lynch said police were canvassing service stations in the area in the hope of connecting a purchase with the homicide. 

Police believe Prasad had driven himself to Plunkett Ave, about 27km from where his body was found. His car's steering lock was found inside his vehicle. 

Lynch said that indicated "he got into another vehicle".

Police have checked CCTV footage of where Prasad's 4WD was parked, but the angle of the footage only gives a peripheral view of Plunkett Ave, Lynch said.

Detectives are now extending their search along Cavendish Dr.

Prasad's wallet and car keys are still missing.

On Wednesday, police recovered Prasad's mobile phone "with the assistance of a member of the public", but are satisfied that person was not involved in his death.

Police are seeking sightings of two cars seen speeding away from McRobbie Rd around 6.30am the morning Prasad's body was found. 

It is unknown if the vehicles are relevant to the investigation.

Anyone with information about Prasad's death is asked to call police on 09 295 0311 or Crimestoppers on 0800 555 111.

- © Fairfax NZ News