BERKELEY, Calif. (KGO) -- The FBI is now involved in the investigation into violent protests at U.C. Berkeley over an appearance by controversial editor Milo Yiannopoulos.FBI agents say they have been in contact with U.C. Berkeley over the incident which led to President Trump tweeting a threat to pull federal funds from the school.Berkeleyside reports that investigators are trying to figure out who caused $100,000 worth of damage at Sproul Plaza.Cal blames a group called Black Bloc - who are not students.The violence forced the cancellation of a planned speech by the self-proclaimed internet troll.Yiannopoulos has said he will return to Berkeley to give the speech but hasn't set a date.