Hey there,
Did you search the murder scene in the north-eastern section? Right click the window, it should say, "Investigate Smashed window" - followed by a chat box: "Some thread seems to have been caught on a loose nail on the window."
It looks like there's one of three types of thread you should be able to receive from the smashed window: Criminal's thread (red), Criminal's thread (blue), Criminal's thread (green). The color you receive is different per player.
If you've tried the above already, what does your quest log say in regards to what you should do next?
Hope this helps.
You can call me Nate.
29-Jan-2023 07:10:44