James Haines McIlveen was a New York City police officer and the partner of Tessa Mancuso. He was shot and killed by Mulwray and his body taken to the Butler Institute, where a copy of his mind was created and uploaded onto a microchip, which became the artificial intelligence of Mancuso's experimental new gun. During a drug store robbery, the gun saved Mancuso's life by shooting one of the robbers by itself. Shocked, Mancuso took the gun to Petersen in R&D, where the Seventh Doctor proved to her that the gun contained her late partner's mind by using a computer to communicate with it.
McIlveen agreed to assist the Doctor in his plan to defeat the Institute, as he wanted revenge for what the Institute had done to him. After Mancuso was shot by Stephanie and placed on life support, the Doctor connected McIlveen's chip to the medical computer so he could watch over her. (PROSE: Cat's Cradle: Warhead)