BUCKLEY, Ill. — A man whose body was found in a tanker truck near Buckley, Illinois in June died of an overdose, authorities confirmed.

Garrett Meyer, 29, of Nashville, Ill. had “toxic levels of amphetamines and fentanyl” in his system, according to autopsy results released by the Iroquois County Coroner’s Office Sunday. He also had a blood alcohol level of .181.

Autopsy results also ruled out any foul play or natural diseases in Meyer’s death. The Iroquois County Sheriff’s Department is still investigating the incident.