Philadelphia authorities should have known that Eric Ruch Jr. had a “prior history of unconstitutional conduct,” and by failing to “terminate, retrain, or discipline” him the Police Department is responsible for his fatal shooting of an unarmed man in 2017, according to a federal lawsuit filed by the man’s widow against Ruch, three other officers, and the city.

Ruch was fired in October 2018 by then-Police Commissioner Richard Ross, who said the 10-year veteran had violated the department’s use-of-force policy when he shot a bullet through Dennis Plowden Jr.’s raised left hand that lodged in his head. Plowden, 25, was sitting on a sidewalk on Opal Street near Nedro Avenue in Germantown, having just stumbled from a car he wrecked while fleeing two unmarked police cars on Dec. 27, 2017.

» READ MORE: 6 months after Philly police shot unarmed man, widow still seeks answers

Ruch had shot another man while on duty 10 months earlier and had engaged in “numerous unlawful” traffic stops and acts of excessive force, according to the suit filed by widow Tania Bond, the mother of Plowden’s 3-year-old son, Darryl Plowden.

Prior complaints and lawsuits had alerted city officials to Ruch’s “prior history of unconstitutional conduct,” according to the suit, filed Friday on Bond’s behalf in U.S. District Court in Philadelphia by Center City civil rights attorney Paul J. Hetznecker.

The Police Department “has a history of condoning unconstitutional conduct committed by its officers,” Hetznecker said in an interview Tuesday. “Accountability is essential to our democracy and this begins with training police officers to respect and protect the constitutional rights of all residents of the city.

“Shooting Dennis Plowden Jr., while he was lying on the ground injured and unarmed is another example of this history. The family is devastated. My client is left without a husband, and her son without a father. Our hope is that through this lawsuit we can achieve a measure of justice for the family while at the same time push for significant reform in an effort to end the legacy of unconstitutional conduct by the police.”

Michael Neilon, a spokesperson for the Fraternal Order of Police Lodge 5, the union that represents Philadelphia officers, declined to comment on the lawsuit. Andrew Richman, spokesperson for the city’s Law Department, which represents the city and its employees in lawsuits, also declined to comment.

Police officials said officers were trying to stop the car, which Plowden had borrowed, because it was linked to a homicide, of which he was not a suspect.

The suit, however, states that Ruch and the other officers’ attempt to stop the Hyundai Elantra driven by Plowden was unlawful because they had no “reasonable suspicion or probable cause” to stop it.

The Philadelphia District Attorney’s Office has not decided whether Ruch committed a crime or justifiable homicide. “This is an open and active investigation, and as such we cannot comment,” office spokesperson Jane Roh said.

District Attorney Larry Krasner, who took office six days after Ruch killed Plowden, was propelled into office in part by a pledge to crack down on violent police officers.

“If we have facts and we have the law, if we follow the evidence instead of following anybody’s politics, and we have a case in Philadelphia County, we are bringing a case,” Krasner had said shortly after taking office.

In another case in which a white Philadelphia cop killed an unarmed black man, Krasner last September charged Officer Ryan Pownall with murder and related crimes in the June 2017 killing of David Jones. Pownall, 37, who was fired in 2017, is free on bail and scheduled to be tried in January 2020.

If Krasner — a former defense lawyer who has sued the Police Department 75 times — files charges against Ruch, 32, it would mark the first time that two former Philly cops would face criminal charges at the same time for on-duty fatal shootings, legal observers believe.

Also named in the Plowden suit are officers Anthony Comitalo, Mike Sidebotham, and Ryan Del Ricci. The suit, which claims that Plowden and his widow suffered various violations of their constitutional rights, seeks monetary damages in access of $150,000.

Staff writer Nathaniel Lash contributed to this article.