Police suspect the people in the car were either witnesses or involved in the shooting.
Bottoms, a sophomore at Atlanta Metropolitan College, and a friend had just gotten into their parked car and were driving away when they saw a person in the crosswalk at the intersection of Sells Avenue and Legacy Drive who made them uneasy, police said.
Bottoms, who was driving, put the car in reverse to go in another direction and that was when multiple shots were fired, according to police.
The friend, who has not been identified, escaped.
Councilwoman Keisha Lance Bottoms has made several public pleas for information in the death of her nephew by marriage.
Initially, the reward was set at $2,000. It increased to $5,000 on Tuesday.
Anyone with information is encouraged to contact Crime Stoppers Atlanta at 404-577-TIPS (8477).