Scrutiny of the engineer who operated a train that derailed in Philadelphia last year, killing eight passengers, isn't over yet.

On Wednesday, the National Transportation Safety Board plans to issue its final report about the May 12, 2015, derailment, and is expected to reiterate its conclusion that engineer Brandon Bostian lost "situational awareness" and accelerated to 106 mph heading into the Frankford Curve, where the speed limit is 50 mph.

Bostian, now 33, was likely distracted by radio chatter about another train that had its windshield cracked by a rock in the same area, the board concluded.

Throughout the year the NTSB spent on its investigation, the Philadelphia District Attorney's Office would only say it was participating in the federal review.

The feds are done now, but the district attorney apparently isn't.

Office spokesman Cameron Kline said the investigation into the derailment remains open. He would not specify what the investigation was focusing on, and District Attorney Seth Williams declined to be interviewed.

Bostian's lawyer, Robert Goggin, did not respond to requests for an interview.

Amtrak has admitted responsibility for the crash, but lawyers representing the injured want something more specific - accountability for the man in the locomotive.

"There are a not-insignificant number of victims who believe that Brandon Bostian needs to be held accountable in a criminal court of law," said Bob Mongeluzzi, who with Tom Kline is representing 30 people injured in the derailment.

Kline suggested the facts leave the door open for a criminal charge.

"It is my considered opinion that there are grounds for charges at a minimum for reckless endangerment based upon conscious and deliberate actions that need to be taken by Mr. Bostian to have the train going 106 mph," Kline said.

Reckless endangerment is a misdemeanor offense in the Pennsylvania criminal code that could apply when a person consciously disregards a risk and as a result puts others at risk of serious injury or death. Meeting the commonwealth's legal definition of recklessness requires a "gross deviation" from normal behavior under the circumstances.

That's a high burden of proof, said Lynne M. Abraham, who was Philadelphia's district attorney for almost 20 years. Abraham said she felt it would be difficult to meet in the Amtrak case.

"A reasonable fact-finder," she said, "would be hard-pressed to find on these facts as we know them at this moment that [Bostian] was criminally negligent."

Bostian was not using a cellphone when the train derailed; he was not intoxicated. He told NTSB investigators his memories of the minutes leading up to the crash are spotty.

While the NTSB did find that the New York-bound train derailed because Bostian made an error, federal investigators emphasized that he was distracted and that Amtrak, by not installing a backup braking system, had created a system in which one mistake could create catastrophe.

That report, Abraham said, will be on the minds of prosecutors as they decide whether to charge.

"I think it will have an appropriate and significant impact," she said. "It's not the end word. They're not looking at the same thing as a prosecutor."

For an investigation to remain open-ended so long after the event under review isn't unusual, Abraham said. The complexity of material, amount of information that needs to be reviewed, and the demands on investigators' times are all elements that can keep a case open, she said, adding, "It's a lot to sift through."

215-854-4587 @jasmlaughlin