The Scarf (1951)

John Barrington escapes from an asylum for the criminally insane and finds refuge on the ranch of turkey-raiser Ezra Thompson. Barrington, who has suffered from amnesia, finds his memory returning slightly and he sets out on his mission of learning the truth about whether or not he really murdered his sweetheart and is actually insane. He goes to Los Angeles to visit his oldest and best friend, psychiatrist David Dunbar, who was a witness to Barrington's crime. Dunbar repeats his story to Barrington, convinces Barrington that he did commit the crime, and then betrays him to the police. However, Thompson, Connie Carter and others are not totally convinced of Barrington's guilt.

IMDb: https://www.imdb.com/title/tt0043998