The suspect has been charged with first degree murder and first degree robbery. His name has not yet been released because of his age.
The other suspected killer is still on the loose.
The Spokane Police Department said in a press release officers responded to reports of an assault and found the victim in his car with serious head injuries on Wednesday evening. He later died in the hospital.
Authorities on Thursday released surveillance photos of the two suspects, who they describe as black males between the ages of 16 and 19.
Friends identified the victim as Delbert Belton, and say he was sitting outside a lodge for the Fraternal Order of the Eagles when he was attacked. He died in the hospital Thursday from head wounds.
KXLY-TV reports that Belton served in Army during World War II and was shot in the leg during the Battle for Okinawa. He was also a lifetime steelworker.
Anyone with additional information is asked to call the Spokane Police at 509-456-2233.