John Halloran seldom played roles with extensive dialogue during his 24-year screen career, but filmgoers found him a memorable figure from his mere physical presence. A martial arts expert and judo champion, he came to films in middle age after a career in law enforcement that was interrupted over his devotion to those very skills that made him so valuable to the police in the first place. In his larger screen roles, starting with the sinister Captain Oshima in Frank Lloyd's Blood on the Sun (1945), he often made use of his specialized fighting skills, while in smaller parts his size and imposing presence were sufficient. The actor's birth name was John R. Sergel -- he was an American citizen born in Argentina in 1902 to Edwin J. Sergel and the former Belle Russell. His interest in martial arts dated at least from the 1920s. According to various sources, Sergel was part of the San Fernando Dojo in 1932, and set several records in judo competitions at the end of the 1930s. He was a member of the Los Angeles Police Department, holding the rank of sergeant in the early '40s, one of several martial arts experts in the employ of the LAPD at the time. But Sergel was singled out for attention by federal authorities after he took several students, including women, to the notorious Manzanar internment camp -- where many of the Japanese-Americans in the Los Angeles area were being held -- to get them graded in judo. This led to investigations by both the federal government and the local police; Sergel's loyalty to the United States was beyond question, and his police credentials were impeccable, but his admiration and respect for Japanese culture proved to be too controversial in 1944. He resigned from the police force in October of that year. Almost immediately, Sergel was tapped by actor James Cagney, who was then in the process of starring in and producing the movie Blood on the Sun, to serve as a technical advisor as well as the hero's greatest physical nemesis, Captain Oshima. With this commencement of Sergel's movie career, the martial artist and actor took on the stage name John Halloran. The movie got mixed reviews and was not a huge box-office success, but everyone who has ever seen it remembers the climactic judo fight between Cagney and Halloran that destroys just about everything in the room in which it takes place, as well as savaging the two characters. After that, Halloran went on to appear in more than 60 movies and television shows, sometimes cast as sinister heavies in Westerns, and other times making use of his special skills in more exotic and modern settings. Indeed, for a time he became the judo equivalent of Mushy Callahan, the prize fighter who trained countless screen actors and served as technical advisor on a generation's worth of movies about boxing. Halloran worked with Cagney again on pictures, and in movies as different as the Anthony Mann Western The Far Country (1955) and the Kurt Neumann sci-fi thriller Kronos (1957). He also appeared as himself, referred to as "Jack Halloran," in the Abbott & Costello Show episode "Police Rookies," as a martial arts expert demonstrating various judo holds and moves (udenage, kata guruma, etc.). He worked steadily in pictures almost right up until his death in 1968, and his last screen appearance was in the movie Bob & Carol & Ted & Alice (1969).