After fighting in Vietnam, Cragen began his career as a homicide detective in the 1960s with partner Max Greevey (George Dzundza), gradually rising up through the ranks to police captain and commanding the 27th Detective Squad. At some point, Cragen graduated from St. Raymond’s University, a Catholic university known for its basketball team (SVU: “Sophomore Jinx”). As revealed in the episode “Prescription for Death“, Cragen was an alcoholic for much of his early career, but went sober after pulling his service revolver on a taxi driver in a drunken rage when he was still a detective. He does not touch another drop, even following the death of his wife, Marge, in a plane crash. He occasionally opens up about his recovery; in the SVU episode “Slaves”, for example, he admits to a police psychiatrist that he is daily tempted to relapse in order to escape the horrors he sees every day in his job. In season 11,  Cragen reveals that he has been sober for 20 years.
Cragen mentions having a child, but during his time on SVU, it is stated on more than one occasion that he has no children.
In 1991,  Cragen is investigated by internal affairs for corruption; during the investigation to prove his innocence, he discovers that he is being framed by his former captain and mentor, whom he turns in. In another episode,  his former partner and longtime friend Greevey ismurdered.
Cragen is removed from the series following the episode “Benevolence”; it is later explained that he had transferred to the Anti-Corruption Task Force. He is succeeded as squad commander by Lt. Anita Van Buren (S. Epatha Merkerson).