Barnaby Jones (1973)

Former private investigator Barnaby Jones comes out of retirement to find the person who killed his son Hal. With the aid of fellow P.I. Frank Cannon, Barnaby eventually finds his son's killers. Barnaby then decides to come out of retirement and resumes his practice with Hal's widow Betty serving as his secretary. A few years later, Barnaby's cousin Jedidiah (a.k.a. J.R.), a law student, seeks Barnaby's help in finding the killers of his father. Just like a few years earlier, the two find the men who killed J.R.'s father and as a result J.R. decides to stay on with Barnaby working as his legman while he is studying law. Their contact on the L.A.P.D. is Lt. John Biddle.