Black Party: Ruhe in Frieden, Sherlock

In Black Party the players embody figures who are involved into a spectacular murder case. One of the players is the murderer. But the others also have their dirty secrets or a motive and each of them have an extra task that only they know.
The group decides by guessing and reconstructing the crime who is the murderer and afterwards the players see if the group was on the right track. So it's about getting away with life. Because what good is it to be innocent if the others think you are guilty?

In Black Party - Ruhe in Frieden, Sherlock the world-famous detective Sherlock Holmes was strangled on his way home from his favorite opium den in a cab. Who is the murderer?