Synanon, originally known as Tender Loving Care, was a new religious movement founded in 1958 by Charles E. "Chuck" Dederich Sr. in Santa Monica, California, United States. Originally established as a drug rehabilitation program, Synanon developed into an alternative community centered on group truth-telling sessions that came to be known as the "Synanon Game", a form of attack therapy.
Described as one of the "most dangerous and violent cults America had ever seen", Synanon disbanded in 1991 after several members were convicted of offenses including financial misdeeds, evidence tampering, terrorism, and attempted murder
https://en.wikipedia.org/wiki/Synanon