Ruiz, a correspondent for the regional station Radio Galeón, was killed by gunmen with two close-range shots to the head as he crossed the market square in the northern town of Pivijay at around dusk, police and colleagues said.
Police said they were still investigating the identity of the attackers. But senior colleagues at Radio Galeón, based in the port city of Santa Marta, alleged that Ruiz had been killed by members of a right-wing paramilitary group that operates in and around Pivijay, in central Magdalena Province.
These sources told CPJ that the group was not linked to the United Self-Defense Forces of Colombia (AUC), a nationwide alliance of right-wing groups, but was rather a gang of hired gunmen financed by "the rich people in the area."
"That whole area is virtually off limits for the press, the police, and the army. It's an island where an illegal group is in charge," one of Ruiz's colleagues said.
One of the dead man's relatives told local journalists that gang members had threatened Ruiz on two recent occasions, telling him to stop reporting bad news about Pivijay and to "give up that big mouth's job."
Ruiz had worked for Radio Galeón on a freelance basis for the last three years, covering politics, crime, and general news in and around Pivijay. He was a self-taught journalist who started his radio career about 15 years ago at Radio Libertad, another regional station headquartered in the port city of Barranquilla. Ruiz also worked with a community radio station in Pivijay and ran a small grocery store in the town.