The Alfred Hitchcock Hour (1962)

S1E21 I'll Be Judge, I'll Be Jury

While vacationing in Mexico, Laura Needham is killed, leaving her husband Mark devastated. He learns that the local police have taken an American named Theodore Bond into custody as a suspect, but they can't build a solid case against him. Determined to find evidence, Mark takes matters into his own hands, only to fall victim to Bond's violent intentions. Grieving and outraged, Laura's in-laws, Alex and Louise Trevor, resolve to see Bond brought to justice. They devise a plan, using Louise as bait, and successfully catch Bond in the act of trying to commit another murder.