The body of a decomposed man was found in an abandoned building in Hayward on Tuesday morning, a police lieutenant said.

A construction worker detected a foul odor and followed the scent into the building that was formerly Perry & Key Body & Paint Shop at 28953 Mission Blvd. at about 9:30 a.m. Tuesday, Lt. Roger Keener said.

The worker found the man and reported it to police. The man had been in the building for around one to three weeks.

Because of the deterioration of the body, there were no visible signs of trauma to the body, Keener said.

The Alameda County coroner's bureau was expected to conduct an autopsy to determine the identity of the man and the cause of death, Keener said.