What niche investigative true crime podcasts beyond mainstream would you suggest?

[Penelope42]

I've burned through most of the mainstream true crime podcasts and am looking for recommendations that go beyond the typical serial killer narrative, focusing instead on well-researched deep dives into white-collar crime, historical mysteries, or complex conspiracies. Production quality and respectful handling of victims are really important to me, as I find some shows can be overly sensational. For fellow enthusiasts, what are some lesser-known or niche podcasts in the genre that you consider hidden gems, particularly those with a investigative journalism approach rather than just a conversational recap?