More than one dozen arrests were announced Friday by the FBI and the L.A. County Sheriff's Department - after a year-long investigation confirmed a series of assaults on inmates were being directed by members of the Mexican Mafia prison gang.
Deputies and agents eventually intercepted phone calls that showed how attack messages were being exchanged.
"Mexican Mafia facilitators relayed orders to Mexican Mafia associates, known as soldiers, that were incarcerated in the jail system to assault or murder other inmates who were perceived to have violated the Mexican Mafia rules," said Sheriff's spokeswoman Nicole Nishida.
The charges include allegations the communications led to at least two inmate stabbings.
Authorities said on two occasions attacks were prevented when orders were monitored and the targeted inmate was placed in protective custody.