Calgary police are investigating a homicide after a man injured in a serious assault died in hospital on Monday.

Police found the victim, now identified as Darrin Thomas Amond, in the parking lot of the Whitehorn Safeway in the city's northeast nearly two weeks ago.

Amond was found by police on July 18 after being flagged down by a citizen.

"Officers pulled over and provided first aid," reads a news release. "The man, whose injuries are believed to have been caused by a serious assault, was taken to hospital, where his condition deteriorated."

Police said they believe there were witnesses to the assault, which took place in the middle of the afternoon, and hope those with information will come forward.

Victim was previously sentenced

CBC News has confirmed that Amond was previously convicted of manslaughter for his role in the beating death of a stranger, Marcus Tremaine Deveaux, in 2011.

Darrin Thomas Amond seen in this file photo from the time of his manslaughter sentence. (Facebook)

Amond was sentenced to four years in prison for what was described as an unprovoked attack on Deveaux, who was found in an Inglewood snowbank in 2010.

He had been beaten for not being able to provide his attackers — Amond and Richard Ceasor — with a cigarette. He was taken to hospital but later died of his injuries.

Police said at that time that the assault was random and Deveaux did not know his attackers.

Those who witnessed the recent assault on Amond, or know anything about the incident, are asked to contact the homicide tip line at 403-428-8877, the Calgary police non-emergency line at 403-266-1234 or anonymously through Crime Stoppers.