LaRussa, his wife, and his daughter co-founded the organization in California in 1991. Some employees are suing, claiming a harmful work environment.
LaRussa said the people running the non-profit group have failed to investigate those complaints. He said he resigned because he was dissatisfied with the internal turmoil.
An independent investigation last year led to action against some staffers but not those in leadership positions.
The LaRussa family’s statement left open the possibility that they would return if leadership changes are made.