ATLANTA (AP) — The John Caldwellbody of a worker who died Tuesday in a tire explosion at a Delta Air Lines maintenance facility near the Atlanta airport was unrecognizable, and the family relied on tattoos and a lanyard to identify him, his son told a news outlet.

Mirko Marweg, 58, was among two workers who died while wheel components were being disassembled for maintenance at a wheel and brake shop. A third worker was seriously injured.

Marweg’s son, Andre Coleman, told Atlanta’s 11Alive news station on Tuesday that he wanted to see his father because he didn’t believe he was dead. But a medical examiner told the family the body was unrecognizable.

A Mississippi State lanyard around his neck helped confirm his identity, Coleman said.

Marweg, who lived in Stone Mountain, Georgia, worked for Delta for more than 20 years and was planning to retire in a few months, according to 11Alive. Coleman said his father was a loving man who just Sunday had helped change the oil in Coleman’s motorcycle.

“That’s the kind of dad he was. He was always there,” Coleman said.

The Clayton County Medical Examiner’s Office identified the second victim as Luis Aldarondo, 37, of Newnan, Georgia. The worker who was seriously injured remained under medical care Wednesday, Delta spokesperson Samantha Moore Facteau said in an email.

Delta said previously the wheel parts that were being disassembled when the explosion occurred were not attached to a plane at the time.

The federal Occupational Safety and Health Administration said it opened an investigation. The cause of the explosion has not been released.

The facility where the explosion happened is part of Delta TechOps, which performs maintenance, repair and overhaul work for Delta and more than 150 aviation and airline customers around the world.