Pennsylvania’s top prosecutor Friday charged a speeding Amtrak engineer with causing a “catastrophe’’ in the deadly 2015 derailment that came when he accelerated to 106 mph on a 50 mph curve.

Pennsylvania Attorney General Josh Shapiro expanded on charges a judge had approved a day earlier.

The judge’s unusual order came after the family of a woman killed in the crash sought a private criminal complaint — allowed under Pennsylvania law — against Brandon Bostian, who lived in Queens at the time of the derailment.

Philadelphia prosecutors had declined to press criminal charges as Friday’s two-year deadline approached.

Shapiro filed the felony “catastrophe’’ charge along with misdemeanors counts, including eight counts of manslaughter and reckless endangerment.

Lawyer Thomas R. Kline, who represents the family of victim Rachel Jacobs, said the engineer would not have been held to account had “a courageous family . . . not stood up against the decision of a local prosecutor not to press charges.”

The crash killed eight people and injured some 200 others.