The truck driver whose vehicle slammed into a state trooper's car on the Tri-State Tollway last month fell asleep at the wheel, according to a report issued by Illinois State Police.
The March 28 crash on I-294 near Willow Road killed 28-year-old Illinois State Trooper James Sauter, of Vernon Hills.
According to the report, the driver of the United Van Lines semi-truck was southbound near milepost 48.5 when he fell asleep about 11 p.m. and veered to the left, striking Sauter's vehicle from behind. Sauter was parked on the left shoulder.
A witness told investigators that the semi truck was already in the left lane before the crash.
Illinois State Police spokeswoman Monique Bond said the investigation is ongoing and charges are pending. She added that the traffic crash report was preliminary.
"There is still a reconstruction report that needs to be completed," she said. "These are very comprehensive reconstruction reports."