I just read an old [1940s?] mystery where the culprit records himself on a new fangled phonograph record and then uses that to cover his crime. His employees know he’s in the habit of locking his door and playing loud music/talking to himself while he works, so no one suspects locks the door to his office. Later they all swear he was at work when the murder occurred.
William Gibson pointed out that during the Depression someone could buy a workshirt for about 35 cents and wear it every day to the coal mine, until it was time to pass it on to their kid.