Sort of. If one person has been paid in crypto for a contract killing and other participants either know that they are facilitating the laundering of illegally-obtained money or suspect as such, then they are culpable.

I haven't really been paying much attention to the mixer thing and I'm not an expert, but the gist is that if you build a big cash blender with the explicit purpose of masking the origin of money, then you are very clearly and willfully facilitating money laundering. If you participate in this money blender, then you are probably assisting in money laundering. The whole thing is shady by nature.