The Duke (miniseries)

The Duke is an American television miniseries that aired on NBC from April 5 to May 18, 1979.
Overview.
"The Duke" follows an aging boxer who became a private investigator. This Chicago, Illinois-set series starred Robert Conrad as Oscar "Duke" Ramsey; Conrad was actually a professional fighter in his own early years.
The executive producer was Stephen J. Cannell, the show was produced by Stephen J. Cannell Productions, in association with Universal TV.