Investigators did not find any evidence of drugs or alcohol in Bostian’s system or find evidence he was distracted by a cellphone or other device.
Victims' lawyers Tom Kline and Robert Mongeluzzi described their clients as bitterly disappointed and said many remain in constant pain two years later.
"There are people in relentless, debilitating, brutal pain, who have lost their jobs, and who have lost their futures, because of Mr. Bostian's actions," Kline told The Philadelphia Inquirer last week. "I think it becomes even more important to hold people like him responsible."
The Associated Press contributed to this report.