A number of decades ago, this colorful sub-genre of film was very popular on another continent. They were primarily made in one country that gave the sub-genre its name but other countries on the same continent also made these type of films. They later proved to be very influential on a sub-genre of American film as well.
There were hundreds of films made that ranged from popular classics (including the work of this A list director whose family member has been in the news a bit the last few years) to a lot of cheaply made B movies.
At the same time, there was a lucrative underground business in snuff films on this continent -movies of real people, usually young women, being murdered.
The people who made these films found a way to get their product out right under the nose of authorities. Put real murders in the booming sub-genre's films. The A list director's films of course did not contain murders but many of the b movies that he helped finance behind the scenes did. He got very wealthy from his dealings with the snuff merchants.
One telling detail - Look at any old lower budget film of this sub-genre and look at some of the actresses who get murdered who are not stars, the ones who get killed earlier in the films. There is no trace of them anywhere after the films they starred in.
Giallo films/Italy/Dario Argento/Asia Argento