I'm also interested in how they worked in other historical Islamic Middle Eastern societies (such as the Ottoman Empire, Fatimid Caliphate, Ummayad Caliphate, etc), so if you know about them feel free to reply. I just knew if I said "how did criminal investigations work historically in the Middle East" people would immediately (and rightfully) point out that's a huge area and timeframe!

Also, did the order of assassins of which the Assassin's Creed video games based off of ever play a role similar to the Spanish inquisition, investigating religious deviances? If not, legal?