DENVER -- An autopsy report on the woman who died when the bus she was driving crashed into a concrete pillar at Denver International Airport showed she had no drugs or alcohol in her system.
"In our opinion, this 43-year-old female, Kari Chopper, died as a result of blunt force injuries, which were sustained when the bus she was driving impacted a concrete pillar," the report from the Denver Office of the Medical Examiner said Wednesday.
"Toxicological testing performed on postmortem heart blood was negative."
Chopper's husband, Josh Chopper, said last month that his wife had no existing medical conditions, and she did not use drugs or alcohol.
"Of note, a natural event such as cardiac arrhythmia or syncopal episode may have occurred prior to the crash; however this cannot be confirmed with any degree of certainty," the report said.
"With the information available to us at this time, the manner of death, in our opinion, is accident."
Chopper was driving a school bus for Legacy High School when she crashed on Sept. 11.
The bus was part of a convoy that was returning the varsity and junior varsity football teams to the school after a trip to Southern California for games. Eighteen others -- 15 players and three coaches -- aboard were injured.
The bus had no signs of mechanical issues, the Denver Police Department said.
“The mechanical inspection turned up no obvious precrash issues,” police spokesman Doug Schepman said in a statement.