Gaddis, of Palos Hills, was transported to Stroger Hospital where he was later pronounced dead, officials said.
Police say the offender arrived at the station in the 600 block of West Harrison Street from Minneapolis, Minn. The suspect then waited for the victim to arrive, approached him and fatally shot him.
The suspect changed his clothes at the station then left, according to police.
Police are searching for a Black man, around 5'10-6', 200-225 lbs., with a beard.
Before the shooting, police say the offender was wearing a baseball cap, blue surgical mask, grey hooded jacket, blue athletic pants with two white stripes down each leg, and blue Croc style shoes.
Man wanted by CPD in connection to fatal shooting at Greyhound Station.
The backpack as seen in above picture was left at the scene and has been recovered.
After the shooting, the offender changed clothes into a black Reebok hooded sweatshirt, with Reebok on the front in white lettering, a black balaclava style mask, and has a blue suitcase.
Contact Chicago police with any information on this individual.