» UPDATE: Prosecutors on Oct. 21 said evidence refutes claim that passengers may have filmed the rape of a woman on a SEPTA commuter train instead of calling police. Read more.

Passengers who witnessed the rape of a woman on a SEPTA train last week but did not intervene or call police as it was happening will not face criminal charges — because state law does not permit it, Delaware County District Attorney Jack Stollsteimer said Wednesday.

Stollsteimer said in a statement that although he is outraged that a rape happened in such a public place, “Pennsylvania law does not allow for the prosecution of a passenger who may have witnessed a crime.”

“I will focus the efforts of my office on holding the perpetrator accountable,” the DA said. He also asked anyone who may have seen the Oct. 13 incident to speak with investigators, saying witnesses “should not fear prosecution.”

Authorities this week said that as the victim was being raped on a westbound train last Wednesday around 10 p.m., several other passengers not only looked on but also appeared to point their smartphones toward the assault as it unfolded. Yet the only person to call 911, they said, was an off-duty SEPTA employee.

SEPTA Transit Police officers arrived three minutes after that call, authorities said, allowing them to interrupt the assault and arrest the alleged rapist, Fiston Ngoy, 35.

Upper Darby and SEPTA police officials said riders should have taken steps to report the assault. Upper Darby Police Superintendent Timothy Bernhardt called it “troubling” that no riders had taken any action.

According to charging documents, the victim told police she had a few beers after work, then got on the wrong train at 9:15 p.m. at the Frankford Transportation Center in Northeast Philadelphia.

About a minute later, the documents say, Ngoy entered the train, began to talk to the woman, then moved to the seat next to her. She repeatedly pushed Ngoy away as he attempted to touch her and at one point grabbed her breast, according to surveillance video that captured the encounter.

“Throughout this time, the victim is obviously struggling with keeping him off of her,” investigators wrote in charging documents.

At 9:52, documents say, Ngoy raped the woman. He was taken into custody by responding SEPTA officers after the train pulled into the 69th Street stop in Upper Darby.

Ngoy later told police he had seen the woman before and struck up a conversation before kissing and touching her, the documents say. He told investigators she initiated the sexual encounter and did not resist his advances.

The victim told police she had never seen Ngoy before and never gave him permission to touch her.

Ngoy faces charges including rape, involuntary deviate sexual intercourse, and sexual assault. His public defender on Wednesday declined to comment.