OAKLAND -- The death Friday of a 39-year-old man was declared a homicide Monday after the Alameda County Coroners's Office determined he died from injuries suffered in a beating, authorities said.

The ruling makes the death of Aaron Lang the city's 123rd homicide of the year, 13 more than all of last year.

Lang, of Oakland, had been at Highland Hospital since Dec. 9.

Officer Leo Sanchez said police believe Lang suffered his injuries in an altercation with someone Dec. 8 near the intersection of East 15th Street and 23rd Avenue. Police are trying to determine what the fight was over.

Afterward, Lang, who appeared lethargic, was taken in by a friend in the area, police said. But the next morning he was unresponsive and was taken to Highland Hospital where he eventually died.

Police are trying to locate the person Lang had the dispute with.

Police and Crime Stoppers of Oakland are offering up to $10,000 in reward money for information leading to an arrest. Anyone with information may call police at 510-238-3821 or a tip line at 510-773-2805.