Police are investigating the circumstances surrounding the death of a man who was found unconscious on a footpath at Prospect in Adelaide's north this morning.

Key points: Police say the man was alive when he was found about 5:45am

Police say the man was alive when he was found about 5:45am The 43-year-old from Bedford Park sustained a wound to the chest

The 43-year-old from Bedford Park sustained a wound to the chest He is believed to have been assaulted a short time earlier and was pronounced dead at the scene

Matthew Scott Bristow, 43, had a puncture wound to his chest and was found lying on the footpath on Alabama Avenue, near Prospect Road, about 5:45am.

Investigating officers found Mr Bristow's car — a grey 2006 Ford XR6 Falcon with South Australian registration S842AJZ — at Kidman Park after it was suspected of being stolen.

Police said they were alerted to the abandoned vehicle after a member of the public reported seeing it being driven erratically about 1:20pm.

Matthew Scott Bristow was found dead in Prospect. ( Supplied: Facebook )

"A man and woman were located nearby, and they have been arrested in relation to the theft of the car," police said in a statement.

"They are also assisting police with their enquiries in relation to the man's death."

Earlier, a member of the public alerted police to the man's body.

"Despite the efforts of paramedics, the man was pronounced deceased at the scene," police said.

Crime scene tape was placed along a section of Alabama Avenue and outside a house on Prospect Road.

Acting Detective Superintendent Billy Thompson said the circumstances surrounding the death appeared to be suspicious.

"He was still alive when he was discovered, all indicators are that he has been assaulted further down Alabama [Avenue]," he said.

"He appears to have walked up the street to the junction here at Prospect Road where he has collapsed and subsequently died."

Superintendent Thompson said it was likely the assault occurred "minutes before" he was found.

Police at the scene where a body was found in Prospect this morning. ( ABC News: Chris McLoughlin )

Jogger noticed blood on pavement

Prospect Road was closed to all traffic in both directions this morning between Regency Road and Livingstone Avenue.

Alabama Avenue was closed from Prospect Road as a forensic team examined the scene.

Police were already in attendance when another passer-by, Kilburn resident Elliott Cragg, ran past this morning.

He said he saw what appeared to be blood on the pavement, and said the area had "a bit of a reputation".

"When I moved to Australia I didn't think this situation would be happening on my doorstep," he said.

"It's not really the start I wanted for the morning but it is what it is."

Police have urged anyone who saw or heard anything suspicious in Alabama Avenue or nearby overnight to contact Crime Stoppers on 1800 333 000.