The Alfred Hitchcock Hour (1962)

S3E29 Off Season

Johnny Kendall, a hot-headed cop, gets dismissed from the force and reluctantly takes a job inspecting vacant summer homes during the off-season. Meanwhile, his girlfriend Sandy starts working as a waitress to help make ends meet. While on the job, Johnny learns that the previous deputy was let go due to an affair with an unidentified woman in one of the homes. Jealous and suspicious when he spots the ex-deputy near Sandy, Johnny's paranoia escalates. One night, convinced they are together, he grabs his gun and searches the empty houses. He finds one broken into and, hearing voices inside, fires blindly, only to later discover he has killed the sheriff's wife, not Sandy.