But, is it wrong, perhaps even sinful, to enjoy this entertainment? Could it be seen, in the Catholic perspective, as glorifying evil?
Depends on what you are reading and watching it for.
I’ve been a true crime fan since way before it was popular. I read my first true crime books in high school. I used to read crime stories in the newspaper as a child and teen. My mother would try to hide the paper from me when I was a child because she didn’t want me to get bad dreams from reading gory murder stories, but I never got bad dreams. At this point I’ve read literally hundreds of books, watched literally hundreds of documentaries, and belong to a very large true crime discussion group.
I credit my interest in true crime with influencing me to go back to school in my 30s and become a lawyer. I learned a lot about the legal system reading those books (there weren’t many documentaries then, nor were there dedicated cable channels for true crime shows then).
I see nothing wrong with reading/ watching it in order to know more about how criminals think or how investigators and police work, or how society deals with difficult issues of justice, or to learn how to better protect yourself and your family from threats.
If you’re reading/ watching it because you get excited reading about gory murders, or gory executions, or it’s tempting you to go out and commit crimes yourself, then stop.
This is like every other thread on “is it okay for a Catholic to read/ watch this.” Some of us do just fine with it and other people might be led into bad temptations. It’s a matter of prudential judgment.
Incidentally, if you think true crime “glorifies evil”, then that makes me think you have not read or watched very much of the genre. There is much more glorification of evil in the fictionalized gangster/ thief/ superhero/ horror etc movies than there is in reading the cold hard facts of what actually happened and how it affected real live people.