Officials released a photo of the man they are trying to track down.
He is described as a man in his 40s, with a thin build and a mustache. He was last seen wearing a black "Guess" hooded jacket, distressed blue jeans, black Nike Air Max Goadome boots and white headphones.
He is also known to frequent the area of 40th and Market streets, according to police.
The shooting happened on April 6, around 4:40 p.m., in the 4000 block of Market Street.
The alleged gunman then fled on an electric scooter.
Police said the suspect was dressed in all black and was wearing glasses and a ski mask at the time of the shooting.
The victim, 26-year-old Savion Pollard-Poulson, was found inside the vestibule of the 40th and Market Grocery, suffering from gunshot wounds. He later died at the hospital.
Police said the victim had been inside the store for some time, speaking with another individual, when the suspect entered with a gun drawn.
"Everything that transpired took place inside the store. There was approximately three other people inside that small store," Capt. Timothy Stephan, with the Philadelphia Police Department, previously told Action News.
According to police, an exchange occurred between the victim and the shooter moments before the gunfire.
"Inside that vestibule area, the victim, a 26-year-old black male, was approached by the shooter, who entered the store, gun drawn. Words were said between the shooter and the victim," Stephan previously said.
Investigators said the suspect then fired two shots, striking the victim once in the leg area and in the chest.
Surveillance video suggests the suspect and victim may have known each other, but it is unclear whether the shooting was targeted.
The killing marks the second fatal shooting at the market in recent years. In 2023, a 21-year-old man was shot multiple times in the face and chest at the same location.
Anyone with information can call or text Philadelphia police at 215-686-TIPS (8477) or submit an anonymous tip online.