Former 400-meter world champion Antonio Pettigrew was found dead Tuesday, the university where he worked as a coach said.
Pettigrew, who is survived by his wife and son, had been an assistant track coach at North Carolina for the past four seasons.
The 42-year-old Pettigrew, who was stripped of an Olympic gold medal in 2000 after admitting to doping, was found unresponsive by friends in the back seat of his vehicle in Chatham County in central North Carolina early Tuesday.
County officials said there were indications Pettigrew, who won his world title in 1991, might have taken a sleep aid but were unclear if that caused a role in his death.
•World 100-meter record holder Usain Bolt will not run again this season because of a back injury, his agent said.
Bolt, beaten by Tyson Gay in Stockholm on Friday, was examined Monday by a Munich doctor who found a problem with the Jamaican's lower back, which if not treated could cause injury to his hamstring or calf muscles.