Prout originally gave a statement to police identifying the shooter, and then recanted in court.
Prout's killing had "absolutely nothing" to do with his testimony in that case, said Homicide Capt. James Clark Monday.
Prout's killing appears to be related to a domestic dispute, said Clark, who said he could not comment further since investigators are actively working the case.
Prout had six prior arrests, including for drug offenses, and was on probation for a weapons conviction at the time of his death. Police found him unconscious and bleeding from his head on the sidewalk. He died shortly after at the hospital.
He had been the first witness called to testify at a February preliminary hearing against Daniel Shelley. Prosecutors allege Shelley shot Nurid-Din when he opened fire on a group of young men on a corner near her home.
In a statement Prout gave to police the day after Nurid-Din's murder, he said he saw Shelley, who he knew from the neighborhood, pedal up to the corner and pull a gun from his hoodie. Then he heard the shots, Prout told police.
But on the stand, Prout changed his story, telling assistant district attorney Brendan O'Malley he did not know Shelley and had never seen him.
"No, I don't remember that," Prout said of his statement to police.
In court, Prout would only admit to lifting a dying Nurid-Din into a car, so her family could bring her to the hospital.
Despite the recantation, prosecutors can still use Prout's initial statement at trial since it was read into the record and a defense attorney had an opportunity to cross-examine Prout at a preliminary hearing.
Shelley's trial is set to begin April 15.
Anyone with information on Prout's murder are urged to call homicide at 215-686-3334.
Contact staff writer Mike Newall at 215-854-2759 or email@example.com.