A man charged with killing a Lakeside High School teacher entered a plea of not guilty, police said Monday.

A DeKalb County grand jury indicted Ramiro Pedemonte, 20, last week on charges of homicide by vehicle, serious injury by vehicle and reckless driving for his involvement in a deadly crash on the way to the high school prom on April 25, 2015, Megan Matteucci, an assistant district attorney for DeKalb County, said.

Pedemonte, who was 19 at the time, was travelling in excess of 100 miles per hour when his Dodge Charger T-boned the driver's side of a Hyundai Sonata driven by Leah O'Brien.

He was driving his date to prom when the cars collided on Scott Boulevard at Ridley Circle in Decatur. Pedemonte and his date were taken to the hospital with non-life threatening injuries, but O’Brien, a science teacher at Lakeside High School, was killed in the crash.

Her 8-year-old daughter was in the backseat and severely injured in the crash.

"(O'Brien) was always at the prom," Lakeside Principal Jason Clyne previously told The Atlanta Journal-Constitution. "She was one of the regulars."

Lakeside students didn't find out why their teacher didn't make it to the dance until the next day.

Clyne added that the students were unaware that they had collided with their own teacher until the next day.