Richard Widmark’s only TV series, Madigan (1972-1973), shown under the umbrella of The NBC Wednesday Mystery Movie, was based on his 1968 big-screen picture of the same name. The series had its attractions, but it was considerably less popular than the original film, generating only a half-dozen 90-minute episodes--which explains why it has never enjoyed a formal DVD release in the United States.
However, some kind and most generous soul has just posted all six of those Madigan eps on YouTube (uploaded, apparently, from a French source, since they all feature French-translated opening titles). You can watch the first one, “The Manhattan Beat,” right here. There are links from that same page to the remaining five installments.
Since YouTube is notorious for expunging copyrighted material from its site, my advice is to watch all of Madigan now, or else download the episodes to your computer as soon as you can.