Authorities have identified skeletal remains found by a contractor last November in an underground vault of an Blue Island oil refinery that’s been closed for almost 20 years.

The body of Thomas Michael Whitmer, 57, of Blue Island, was found Nov. 7, 2019 by a contractor at an underground electrical vault at an industrial site in the 3100 block of West 131st Street according to the Cook County sheriff’s office.

An autopsy found his cause and manner of death were undetermined, the medical examiner’s office said.

The sheriff’s office said there were no signs of foul play, and that the body was wearing blue jeans and gym shoes.

The medical examiner’s office said the remains were found at 3133 131st Pl.

That’s the site of a former Premcor Inc. oil refinery, which shut down in 2001 after operating there since 1945. The refinery had been cited for environmental and safety violations.

A spokesman for the sheriff’s office did not know how long the remains might have been at the site, whether it appeared the man was locked inside or who owned the vault.