Little is nown of Jonesey's past, other than that he became a detective and the partner of John Hobbes, a partnership which lasted over twelve years. He implied in the film he was a married man.
Jonesey made his debut in the film at a bar with some of his peers, his partner, Detective John Hobbes arriving after the execution of serial killer Edgar Reese, and them all having a humorous conversation. The next day, after conversing with Hobbes about Reese and being informed of how the latter had received a phone call in the same way Reese would call him the previous night, Jonesey and Hobbes went to an apartment Hobbes was told over the phone about where he could find a clue. There they found a dead body killed in the same style to how Reese would murder his victims, Jonesey showing Hobbes the clue written on the wall, which was a riddle Hobbes then revealed Reese had told him before his death. As their investigation continued, it became apparent that a copycat killer to Reese was responsible. Jonesey voices the situation to Hobbes, explaining that the killer was left-handed, had bad teeth(determined from a chip he found in a bowl of cereal), and had dark hair. Jonesey watched a tape of Edgar Reese with Hobbes, questioning whether a language he was speaking in the tape was Dutch like Reese claimed a later one was, being answered that it was gibberish. Another murder soon occured in Reese's style, a man who lived under an alias and an illegal alien, Jonesey commenting that the killer seemed to be laughing at them. After playing Reese's tape for a language specialist, Jonesey informed Hobbes he would be coming down, stating he seemed to think the unknown language Reese spoke sounded mid-eastern. The specialist identified the language as Sirian Aramaic, which puzzled Jonesey and Hobbes. When he offered to help translate it, Jonesey thanked him and told him to wait out front, before conversing with Hobbes about how he'd seen Reese was right-handed in high school, though in the video he was left-handed, something which Jonesey was prompted to declare senseless since that was little compared everything Reese did. Some time later, Jonesey found Hobbes and told him of the second victim's true identity and that he was apparently the killer of the first victim, but they agreed that both were probably killed by the same killer, Jonesey noting this case gave him a bad feeling.
Jonesey read the translation of the Aramaic to Hobbes after it was faxed over, but stated it made no sense to him. After Hobbes was forced to kill a school teacher who open fired on him on the street, Jonesey noted that it seemed to be some kind of cult responsible for the murders and this happening after the investigation started, Hobbes being seen as a murderer. Later, at the station, Jonesey conversed with Hobbes before he went home about fate. The next morning, following testaments from "witnesses" to the teacher's death, which indicated it was a murder, Jonesey phoned Hobbes and warned him he would be brought in for "more conversation" on the subject. After Hobbes evaded the police, Jonesey called him on his cell phone and asked him what he planned to do, his conversation being tapped by his boss, Stanton. Jonesey was later possessed by the demon Azazel, and forced to accompany Stanton to arrest Hobbes at a mountain cabin. Once there, Jonesey appeared to still be himself at first, and wanted to make Hobbes disappear, but Stanton talked him down, and they forced Hobbes to put down his weapon. Jonesey then, under Azazel's control and direction, shot Stanton through the head, before pursuing Hobbes into the cabin. Before Azazel could forced Jonesey to commit suicide, Hobbes stopped him and they fought for control of the gun, in which Jonesey was mortally wounded. After Hobbes conversed with Azazel, who he'd been trying to find a way to stop after learning the demon was killer he was after, he reluctantly shot Jonesey in the forehead and killed him to force Azazel out of his body.
Jonesey was a very skilled police detective, equally so to his partner Detective John Hobbes.
Jonesey was very good friends with John Hobbes, having been partners with him for over twelve years. He was serious about his job, and seemed to enjoy food, especially Italian food, like pizza.