The victim was identified as Tyrone Hardin, a married father of a 5-year-old son who worked two jobs. His family asked the public for help with information about the shooter.
"He would crack jokes," his sister Michele Hardin told reporters on Sunday. "We would just laugh because he said something or just to seeing him coming you would just laugh because you wouldn't know what to expect. He was was that type of person."
Hardin was killed when he encountered a man allegedly fleeing police in a stolen vehicle at about 7 p.m. The driver crashed the vehicle near 159th Street and Park and ran from the vehicle onto the railroad tracks.
The suspect fired more than a dozen shots, hitting Hardin in the stomach. He was was taken to South Suburban Hospital where he was pronounced dead.
The shooter stole the guard's vehicle but then abandoned it in the 100-block of 171st Street of Hazel Crest, according to Harvey spokesperson Sean Howard.
"Surveillance tapes have taken us a long way. We can confirm we've seen some images that we feel very confident will lead us to the capture of this individual," Howard said.
The man, considered armed and dangerous, was seen wearing a black sweatshirt and blue jeans, said Howard.
A CN spokesman released a statement saying, "Multiple police agencies continue to investigate the shooting death of a security officer who was tragically killed Saturday evening while on duty at the CN railroad yard in Harvey. The guard worked with a private security firm that assists CN Police. We would like to express our sincere condolences on this tragic loss to the guard's family, friends and co-workers. CN continues to work with local law enforcement agencies on this ongoing investigation."