This comes after the District Attorney's Office withdrew a first-degree murder charge against 28-year-old Mark Dial on Thursday.
Dial will now be tried on a third-degree murder charge next year.
The decision comes after defense lawyers for Dial complained that prosecutors had not turned over an expert witness report they commissioned months ago and planned to use at trial.
The trial date has been pushed back until May to give the defense time to respond to the expert report on Pennsylvania's use-of-force law.
The case stems from a shooting in Kensington in August 2023.
Dial shot Eddie Irizarry, 27, multiple times through the driver's side window during a traffic stop.
Police initially said Irizarry lunged at the officer outside the car but later said the officer's body-worn camera footage made it clear that hadn't happened.
Police officials moved to fire Dial after the shooting, citing his refusal to cooperate with an internal investigation.
Dial and his partner have said they followed Irizarry's car after it sped past them at high speed in a bike lane and rounded a corner, driving erratically and finally going the wrong way on a residential street before pulling into a parking space.
Police body camera footage showed Dial firing a total of six rounds about seven seconds after getting out of a police SUV and walking over to the sedan. The footage also showed Irizarry holding a knife near his right leg.
Philadelphia officer charged with murder in shooting death of Eddie Irizarry; bodycam video released
Dial's partner, Officer Michael Morris, previously testified he saw the driver holding a knife with a black metal handle that could have looked like a gun and the man started to raise it as Dial approached, and he "screamed that he had a knife," although he could not remember his exact words.
On cross-examination, attorney Brian McMonagle played surveillance video with audio he said sounded like someone saying "gun" and then Morris saying "gun, knife" and Morris agreed.
A municipal court judge initially dismissed the case, citing a lack of evidence to support the charge, but a Common Pleas Court judge reinstated the case in October.
In late July a judge turned down Dial's request to move the trial out of Philadelphia.
Shaka Johnson, who represents the Irizarry family, said Thursday there's been frustration over the latest developments.
"With respect to the Irizarry family, they are exceedingly frustrated because it's been sort of a yo-yo effect. At one point, Mr. Dial was out. At one point he went back in. Now it seems like he's going back out. And they have no answers as to why this is happening to this particular case," said Johnson.
Dial also faces a civil lawsuit from the Irizarry family.
The Associated Press contributed to this report.