If I am not wrong you need Deputy rank and then pass a day, then your friend will tell you about juvenile problem and then you go to Wealthy Street, I did it at daylight and one of the random people you may investigate will drop the introduction letter
You have to use Unlucky Charm BEFORE moving to the Commoner Street(Night), if used for Slum(Night) it will spawn the special female(or young) bandit. Then it will guarantee the spawn of the victim or bandit, victim can be found in 3 specific places of Commoner Street.
If it's still not working, it's probably because you are using the version of the first post of the thread and it is sort of bugged. If yes, then download:
#759 v1.3.0(base game) and DLC v2.8.0 (page 40, you overwrite the files of 1.3.0 with it)
#788 as said in this post and then you can download the performance patch 3
#1,034 for faster image loading, uncensor (in-game settings) and translation.
You can also just try my save files (backup your save to not overwrite them)
#764 which should work normally, if it doesn't then it's your game that is with a problem and you should do the downloads I mentioned.