The Carroll County school bus driver whose October 2010 bus crash killed a student on board was reportedly struggling with the side-effects of cough medicine.

Students on that bus told investigators that Kenneth Ross Herringdine appeared drowsy, and even ran over a dog the day of the accident, according to a Georgia State Patrol investigative report obtained by The Atlanta Journal-Constitution.

And although Herringdine tested negative for any traces of alcohol or illicit drugs, a toxicology screen following the deadly rollover wreck showed signs of brompheniramine, an ingredient used in cough medication that can cause sleepiness, fatigue or dizziness, the report concluded.

Rashawn James "Ray Ray" Walker, 17, died from injuries sustained when he was partially thrown through a window and the bus rolled over him. Thirteen more students suffered various injuries.

Herringdine, 59, was a driver trainee at the time and was scheduled to take his test to become a full-time driver the next day.

He was sentenced Tuesday to a year of probation and a fine of $600 for failing to stay in his lane.

But his trainer, who was on the bus at the time of the incident, told investigators she was worried about his performance and that students were afraid to ride with him the afternoon they loaded the bus.

According to the report, Sheri Lyn Davis told investigators that Herringdine "looks straight ahead and is slack with his mirror usage" and "does not pay attention."

When asked if she voiced her concerns, Davis told investigators she did following an incident the morning before the accident when Herringdine ran over a dog in the road.

"If he was paying attention, he could have avoided the dog," she said in the report.

Herringdine had not obtained all of the certifications necessary to drive a school bus full-time with students on board, and Davis, who was authorized to take over if she felt her trainee wasn't driving safely, had a broken arm with a cast on it, and wasn't able to drive the bus.