Robert Jones, 54, was fatally shot on October 3.
Authorities say Detective Christopher Sweeney was stopped on the roadway when Jones approached his personal vehicle.
Man dies after being shot by off-duty police detective in Northeast Philadelphia
That's when Sweeney reportedly opened fire.
Sweeney is a 14-year veteran and remains on administrative leave as the investigation continues.
Jones' family, however, is now demanding Sweeney's arrest.
Police told Action News they can not comment on the ongoing investigation.