The motive of the stabbing is still under investigation.
According to family members, the suspect is a neighborhood thug. They say Graham also had some issues, but say he was trying to get his life back together.
Authorities say the incident began with the argument inside the store. Then, when the victim, his son and the suspect walked outside, police say the argument escalated and the victim was stabbed.
The son apparently tried to hold the suspect, but authorities say he let him go when he realized his father was seriously hurt.
The People's Organization for Progess is planning a peace vigil Wednesday night at the scene.
The store is located on Third Street, between Magnolia and Bond streets in the Elizabethport section of the city.
