Tessa Anne Mancuso was a New York City police officer. Her partner was James McIlveen until he was killed by a sniper, after which he was replaced by Breen. During a drug store robbery, she attempted to arrest the Seventh Doctor, who was at the scene of the crime. He ran off, leading her to the robbers' getaway vehicles. After disabling them, Mancuso returned to her partner, but while they were capturing the robbers she was shocked when her experimental new gun saved her life by shooting one of the robbers by itself. She took it to Petersen in R&D, where the Doctor proved to her that the gun's artificial intelligence chip contained her late partner's mind, which had been copied and downloaded into it by the Butler Institute.
Mancuso agreed to assist the Doctor in his plan to defeat the Institute by helping to rescue Justine from the Institute and taking her to their site in the Catskill Mountains. During the confrontation there, Mancuso was shot by Stephanie, forcing the Doctor to place her on life support. When the medical computer gave her no chance of recovery, he connected McIlveen's chip to the computer so he could watch over her. (PROSE: Cat's Cradle: Warhead)