PHILADELPHIA (CBS/AP) — The Pennsylvania Attorney General’s Office announced Tuesday that it is appealing the court ruling where a judge dropped criminal charges against an Amtrak engineer involved in a deadly train accident.

Last month, Judge Thomas Gehret dropped criminal charges against Brandon Bostian following a preliminary hearing.

The 34-year-old train engineer was facing involuntary manslaughter, causing or risking a catastrophe and reckless endangerment charges for the May 2015 accident that left eight dead and more than 200 injured.

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Gehret said that based on the evidence offered by prosecutors, he felt it is “more likely an accident than criminal negligence.”

“The Office of Attorney General has filed its notice of appeal of the Municipal Court decision in the Amtrak case,” spokesman Joe Grace said. “We are seeking a legal determination based on the proper standard for a preliminary hearing.”

Federal safety investigators concluded Bostian lost his bearings while he distracted by an incident with a nearby train.

The National Transportation Safety Board found no evidence that Bostian was impaired or using a cellphone. The agency also called Amtrak’s long failure to implement automatic speed control throughout the busy Northeast Corridor a contributing factor.

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Earlier this year, the Philadelphia District Attorney’s Office declined to charge Bostian. But then, after the family of a victim who died filed a private criminal complaint, a judge ordered Bostian face charges. The Pennsylvania Attorney General’s Office then decided to handle the case.

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