Update: The Philadelphia District Attorney's Office announced Tuesday that it had completed its criminal investigation and that there was not enough evidence to support filing criminal charges.

Earlier Story

Two years ago this Friday, Amtrak engineer Brandon Bostian drove a seven-car train off the tracks at Frankford Curve, killing eight and injuring more than 150 people.

Bostian accelerated Amtrak Train 188 to 106 mph, more than twice the speed posted for that stretch of track, as it approached the turn just north of 30th Street Station on May 12, 2015, according to findings by the National Transportation Safety Board.

Why he did this remains a mystery. He had no drugs or alcohol in his system and was not distracted by a cellphone, according to the NTSB. Bostian told the NTSB he did not remember what had happened. The federal agency's review concluded that he lost "situational awareness," probably because of radio chatter about a rock hitting a SEPTA train near Frankford Curve, shortly before the derailment.

Lawyers for the injured have never been satisfied with that explanation, and they fear a window of opportunity to hold Bostian criminally accountable may be closing.

Reckless endangerment, a second-degree misdemeanor that carries the possibility of imprisonment, has been discussed as appropriate to the crash's circumstances, and the statute of limitations for that offense expires after two years.

Brandon Bostian

Tom Kline, a Philadelphia lawyer representing a number of victims, says that if no charges are filed by Friday, Bostian will likely never face criminal responsibility.

"If there are charges in a criminal indictment, those charges always include the lesser charges," he said. "If the lesser charges are not brought, we can then conclusively conclude there would be no indictment."

Prosecutors typically prefer to have a wide menu of offenses on an indictment, said Jules Epstein, a Temple University law professor. He added, though, that losing the opportunity to charge a lesser offense does not bar prosecutors from filing more serious charges "if they have evidence to back it up."

Pennsylvania's reckless endangerment statute applies when a person consciously disregards a risk and puts others at risk of serious injury or death. Meeting the commonwealth's legal definition requires a "gross deviation" from normal behavior under the circumstances. Lynne Abraham, a former district attorney, has said she thought meeting that burden of proof would be difficult in Bostian's case because the information available does not clearly indicate that he chose to behave dangerously, as a drunk driver does, for example.

The Philadelphia District Attorney's Office was aware of the coming statutory deadline, a spokesman said Friday.

Bostian lives in a kind of limbo. Along with being the subject of a criminal probe for two years without a charge, he is also on unpaid administrative leave from Amtrak, but he remains an employee. In a brief phone call this week, Bostian said only, "I can't comment at this time."

Bostian's interview with the NTSB is the only public record available in which he describes his experience on the night of the crash.

Amtrak has taken responsibility for the crash and has since installed on its Northeast Corridor rails an automatic braking system that would have prevented the derailment. It has settled claims with 127 people and a process is underway to divide an agreed upon settlement amount of $265 million.

Kline, though, says Bostian himself must be held accountable.

"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," he said. "I think it becomes even more important to hold people like him responsible."

The 34-year-old has left his apartment in Queens where he lived in 2015 to share a first-floor apartment with one other person in a house on a quiet street of large, older houses converted to apartments in Somerville, Mass., a Boston suburb not far from Harvard University.

Bostian did not answer the door during a visit to his apartment this week. He appears to have moved to Somerville in spring or summer 2016, according to a neighbor and property records.

The only insight into Bostian's perspective comes from a lawsuit he filed in January against Amtrak. In the filing, he alleges Amtrak was careless and negligent by failing to provide a safe workplace, proper training, and safety protection. The suit states Bostian suffered injuries to his head, back, and legs, along with psychological injuries. Amtrak has denied the accusations.

The NTSB concluded that if Amtrak had installed Positive Train Control, a braking system that automatically slows a train exceeding rail speed limits, the derailment would not have happened. That system has now been installed on all Amtrak-controlled rail on the Northeast Corridor.

Bostian's Philadelphia lawyer, Robert Goggin, has not responded to requests for an interview.

An Amtrak engineer can be suspended, disciplined, or dismissed only after a formal investigation into the person's conduct in cases involving a serious incident, which includes cases of extreme negligence, according to the Brotherhood of Locomotive Engineers and Trainmen's contract.

A spokeswoman for Amtrak would not provide information on the status of Bostian's internal disciplinary process or say whether one had begun, saying she could not discuss personnel matters. It is unclear how the process might have stretched to two years for Bostian, though the contract does allow delays so the subject of an investigation can call witnesses. That person can also appeal a disciplinary decision.

Representatives of the BLET also did not return a call for comment.

Before the derailment, Bostian was a regular contributor to forums for train enthusiasts, where he posted about his concerns about safety on the railroad. The portrait that emerged was of a conscientious railway enthusiast who criticized railroad officials for failing to adopt some safety measures and who expressed a sense of responsibility for his passengers. He had worked for Amtrak for about a decade and had been promoted to engineer in 2010. He began operating trains on the Northeast Corridor, Amtrak's busiest route, about three years before the derailment. A friend from Bostian's teenage years said he knew no one who loved trains more.

Bostian's upstairs neighbor in Somerville, though, Rachel Sheppard, was surprised to learn he worked in rail. He had never discussed his work with her, she said. She knows him only in passing, she said, but he has struck her as a quiet, nice guy.

"He's always very polite to me and it seems like everyone else," Sheppard said. "He's actually one of the friendlier neighbors in the building."

Inquirer staff writer Chris Palmer contributed to this article.