Bonanza - Season 13 Episode 8 : Face of Fear 1973

Neta, a teen-age girl who is a friend of Jamie's, witnesses an assault and robbery. The victim - Mr. Trumbull, a man who is about to inherit a fortune - dies. The culprit, a drifter named Griff Bannon, gets a glimpse of Neta and, after fleeing the scene, plots to assume his victim's identity and stalk the witness. Her father, meanwhile, is no help, since he raises her by ""traditional values"" and forbids her to socialize with the Cartwrights. Meanwhile, the imposter - now working for the Cartwrights - begins to track Neta's every move and plans to seal her silence, unless she can summon the courage to tell Jamie and the others about the crime she witnessed and identify the baddie.