Police believe the shooting was possibly a road rage incident.
The Georgia-born serial killer produced more than 30 color portraits, which the FBI hopes will help law enforcement match his confessions to victims.
Tens of thousands of people are together in Midtown to mark the 49th annual Atlanta Pride celebration.
Police found the man with apparently shot in the head while sitting in a car.
Police say suspects wanted in the murder of a Gwinnett County man were also involved in another shooting two days later.