On Wednesday, the Oakland Police Department received a call that a dead body was found inside the walls of a historic convention center in Oakland, California.

The said body was discovered in the walls of the Henry J. Kaiser Convention Center around 1 p.m. local time by contractors working on restoring the building. The Oakland Police Department said in a statement that “an unidentified decayed body” and according to the authorities, the adult male victim’s body was described as being in “late stages of decay.”

Lt. Frederick Shavies of the Oakland police department said on Thursday that the victim’s body was found behind drywall and between two concrete pillars in the top tier of the auditorium in a cavity with only a 15-inch opening, according to the Oakland police department. “Markings and biological evidence at the top of the opening indicate the victim may have been deceased near the top and over time his body slowly decayed and slipped toward the bottom of the cavity space.”

Shavies added as he described the dead body “We found remains best described as mummified. The conditions in the walls were such that the body was preserved in good conditions.”

In a video statement, Lt. Frederick Shavies said the victim’s death was likely an accident “caused by positional asphyxiation due to the compression in the small space.”

Watch it here: Facebook/Video

While the age and race have been difficult to determine, it appears that the body has been in the wall for somewhere at least three to five years, he said.

For over 100 years, the Henry J. Kaiser Convention Center has been a fixture in the community. It was built in 1914, the said building “is an Oakland-designated historic landmark and has been rated ‘A’ (Highest Importance) by the Oakland Cultural Survey,” according to the city’s website.

In 2005 the convention center fell into disuse and was closed after the “operating costs became too expensive to sustain,” Oakland said on a page about its adaptive reuse project for the venue. About 10 years later, the city began work to get approval to renovate the space and turn it into a performing arts venue.

Sources: Western Journal, NBC News, Newsweek, People, The Guaardian