Weird Western - Do you Know it?

I have one of annoying / nagging conundrums I need help with as it's really bugging me. A really long time ago (pre 2000!) I saw a disturbing but pretty well made documentary about the wild west and it looked at the dark and unsavoury side of life (well more like death actually). Grainy black and white photos of the departed - and certainly not all 'dearly departed' - and it was morbid but ultimately really fascinating, certainly not one for everyone or family viewing. Not sure I want to watch it again though but would just like to know what it was for my archive lists. Any suggestions Team?