Twenty-eight-year-old Leslie Ruiz-Basilio was killed on May 15 after a suspect shot her during a robbery at the store where she worked off Kirkwood Highway.
Investigators say the killer then took off in Basilio's Cadillac Escalade.
According to Elsmere police, the SUV was found last week in Philadelphia.
Police released an image of a suspect they said arrived on a blue bike, shot and killed Ruiz-Basilio, and then took off in her 2008 Cadillac Escalade. Police also say the suspect may have been seen wearing a fanny pack or pouches around his waist.
"I want them to find him. I want them to find him and they make him pay for what they did to my daughter, because it's not fair," said the victim's mother, Celia Basilio.
The suspect is being considered armed and dangerous.
Anyone with any information is asked to call police at (302) 998-1173 ext. 208.