They have designated chapters on Facebook, Twitter, and numerous other social media sights. Get the URL and charge the owner with terrorism.
Good luck connecting the site owner with the actual thugs doing the rioting and looting though. They’ll just say, “I just want to end racial injustice blah blah blah. I didn’t tell them to smash things.” An examination of the website will show no overt calls to violence, just coded phrases, dog whistles if you will. Enough to cause reasonable doubt in at least one juror’s mind and that’s all it takes.