Updated 12:42 p.m.: Law enforcement reported the dead body to the Los Angeles County Department of Coroner as a "possible gunshot wound,'' assistant chief coroner Ed Winter said Thursday.
An official familiar with the investigation said shell casings were apparently found at the scene of the crime.
Coroner's investigators were expected to arrive on the scene around noon, he said.
Earlier: Angeles Crest Highway three miles north of Foothill Boulevard will likely be closed, in both directions, for several more hours as homicide detectives investigate the area where a motorist found a man's body Thursday morning.
California Highway Patrol Officer Kevin Denmon said the motorist spotted what he thought was a body just after 5 a.m. in the Angeles National Forest. He made a U-turn, saw it was, in fact, a body, and called 9-1-1. Authorities have confirmed it was a male body, but declined to give more details.
As of 10 a.m. officials from the Los Angeles County Department of Coroner had yet to arrive on scene.
Sheriff's Homicide Detective Toni Martinez indicated that the body is not missing 20th Century Fox distribution executive and former UCLA basketball player Gavin Smith.