Tranter said the owners didn't decide to do anything about the filthy apartment until last week, when they paid other tenants in the complex to clean it out.
He said the cleaners began by removing garbage and boxes and buckets filled with human waste.
When they made their way to the bathroom Friday, they found the bathtub filled with dirt and covered with plastic, a sheet and plywood. When they started shoveling the dirt out, they found the leg of a body and called police, Tranter said.
He described the body as part skeleton and partly mummified, and that it had been there at least several years.
"Very unusual, very bizarre," Tranter said. "This guy was literally buried in the bathtub."
Police removed the tub with the body still inside and took it to the Maricopa County Medical Examiner's Office, which is conducting an autopsy.
Tranter said the body may be that of a man who rented the unit in 1995 and was last seen seven years ago. He said the property owners saw a man they didn't recognize at the unit four years ago and asked him who he was.
Tranter said the man identified himself as the original renter. The owners didn't push the issue and continued to receive rent checks.
That man has not been seen since August, and Tranter said police are looking for him.