After being arrested in connection to a homicide in Alabama, Jose Martinez confessed to killing a man on the edge of a wooded area last March. Then he confessed to twenty-nine more murders as he detailed his life as an enforcer for Mexican drug cartels.

As an enforcer with U.S. citizenship, Martinez would be sent to track down affiliates of the cartels who had done them wrong in some way. “I’m the guy that pays you a visit if you don’t pay,” he told investigators.

“Killing people doesn’t seem to affect him,” sheriff’s Capt. Tim McWhorder told CNN. Of the thirty murders Martinez has confessed to, investigators have identified 13 unsolved cases that fit his description.

The murder that got Martinez arrested however, was not connected to the drug trade. While working together on a business (that was, once again, not connected to the drug trade), Jose Ruiz bad-mouthed the girlfriend of a co-worker to Martinez. That girlfriend turned out to be Martinez’s daughter, and two months later Ruiz was dead.

Investigators are now combing the country for cases that fit the descriptions of the murders that Martinez has described, trying to close long since unsolved murders.