OAKLAND, Ca. (KRON) — A body was discovered in the wall of an old convention center in California, police in Oakland have revealed.

Lt. Ray Kelly, the public information officer for the Alameda County Sheriff’s Office, confirmed with Nexstar’s KRON that the decaying body was found in a wall being renovated at the old Henry J. Kaiser Convention Center.

Contract workers found the body around 1 p.m. on Wednesday, according to Lt. Frederick Shavies of the Oakland Police Department.

“The victim’s body was found behind drywall, between two concrete pillars,” Lt. Shavies said in a video briefing, adding that the cavity between the pillars had an “approximate 15-inch opening.”

Authorities estimated that the body had been there for three to five years, but they could not provide a more specific time frame. The victim is believed to be an adult male of unknown race or age.

Lt. Shavies said “biological evidence” discovered near the top of the opening suggests the victim “may have been deceased near the top [of the cavity] and over time, his body slowly decayed and slipped to the bottom of the cavity space.”

There were no visible signs of foul play or trauma, Lt. Shavies said.

Investigators believe the death to be accidental, likely the result of “positional asphyxiation due to the compression from the small space,” according to the video briefing.

Further information on the cause of death and identification will be released by the coroners at a later time.

No other details have been released.

Anyone with information is asked to contact the Oakland Police Department’s Homicide Section at (510) 238-3821 or the tip line at 238-7950.

The Kaiser Convention Center, which opened in 1914, was closed in the mid-2000s as a result of rising operating costs, according to the City of Oakland. In 2015, the city entered into a contract with Orton Development, Inc., to rehabilitate and use the space for commercial purposes and performing arts.