Jack Halford is the highest-ranking ex-officer on the team and the first to be approached by Pullman when she was forming UCOS, Jack is something of a second-in-command to Pullman and acts as a mentor to her on numerous occasions (based on their previous working relationship when she was subordinate to him on the murder squad). Halford retired from the police force to care for his dearly-loved wife Mary who had been involved in a hit-and-run incident; he is still haunted by her death. This is partly due to the fact that no-one was ever charged in connection with it, although it is common knowledge that it was Ricky Hanson (this is proven in Series 4, Episode 1 "Casualty"). Ricky Hanson was finally charged with the death of Mary in Series 6, Episode 6 "The Last Laugh". Halford still speaks to his wife's memorial in his garden, often seeking her help and opinion in solving cases. A softly-spoken and gentle man, he nevertheless possesses a quick and sometimes violent temper that he has unleashed on several suspects in the cases that he has worked on.