South Australian police say they believe a man who was found dead in a house fire in Adelaide's north-west was murdered, with the blaze a deliberate attempt to destroy evidence.

Acting Operations Inspector for Major Crime, Matthew Fitzpatrick said police and emergency services were called to the Woodville Gardens address just after 4am after a passer-by reported seeing the premises engulfed in flames.

"As a result of that investigation, we're satisfied that [the victim] was murdered and that the house was set on fire to deliberately destroy the evidence related to that murder," Inspector Fitzpatrick said.

"The man is believed to be 72-year-old Bill Frangos who lived alone at the house.

"[However], at this time formal identifications have not been completed due to the complexities of the fire investigation."

Inspector Fitzpatrick said the investigation was progressing "very well".

"Despite the fire, we have recovered evidence within the house," he said.

"We know that a jerry can had been set alight on the front grass of that property, we subsequently suspect obviously that petrol was used to start that fire."

Police said Mr Frangos was a long-term resident and well-known member of the community.

"Items usually used to cultivate cannabis have been removed from a number of premises associated to Bill."

Police said they were maintaining an open mind in respect to the motive for the alleged murder and who was responsible.

"[There is] a possibility that the person or persons responsible may be known to him," Inspector Fitzpatrick said.

"We have identified a number of persons of interest, those persons of interest have been spoken to yesterday, they assisted police with our inquiries and at this time we have discounted their involvement."

Police are seeking the assistance of the public in their investigation.

"We're seeking anyone that had contact with Bill in the last six weeks to contact investigators through Crime Stoppers," Inspector Fitzpatrick said.