Well, perhaps Peter's murder may have cast a dismal shadow on Ben's career although "Smith and Jones" does continue for a second season, co-starring Roger Davis.

• Ben does perform in a number of short-seasoned television series during his heyday, however....
• After - Alias Smith and Jones (1971-73)
• The Name of the Game (1968-71), with Tony Franciosa, Gene Barry, and Robert Stack, alternating the leading role.
• Griff (1973-74), with Lorne Greene
• Lottery! (1983–84), co-starring Marshall Colt
• Berrenger's (1985), co-starring Yvette Mimieux, Andrea Marcovicci and Sam Wanamaker.
• Gemini Man (1986), as its primary star.

Ben delivers a fine performance as a drifter trying very hard to reform his ways in

• The Letters (1973) with John Forsythe, Jane Powell, Lesley Ann Warren, Dina Merrill, Leslie Nielsen, Barbara Stanwyck, Ida Lupino, Pamela Franklin and Henry Jones.

Also, Ben guest stars on several episodes of various television series, particularly dramas.

In 1973, Ben does a semi-nude photograph pictorial in Viva Magazine alongside a semi-nude female, so that may also have overshadowed his career with a Himbo image. Ben fans probably would prefer him and him alone.

Other stars of the day were also appearing undraped in those sorts of pictorials, but usually alone, so that makes for a more erotic, less pornographic presentation.

But Ben is good wherever he films, and seems like one dedicated actor even if his opportunities were limited by Hollywood standards.

Why would Duel's suicide affect Murphy?

Hed was not responsible for his death.

I think manfromatlantis means that the suicide had negative impact on the t.v. series they co-starred in; it ultimately wound up cancelled after the replacement co-star and the pairing didn't click with viewers like had the original casting and chemistry. As a result Murphy's career may have wound up losing momentum that it otherwise would have had.

According to Wikipedia:

The series continued for another 17 episodes after the recasting of Hannibal Heyes, but never regained its popularity after the loss of Duel.

I see (per IMDb) that Ben hasn't appeared in anything since 2010. He's currently 77.