Martin Madrigal, 39, was one of 27 people named in an indictment handed up Tuesday in Ventura County, the Los Angeles Times reported. Officials said 24 of the group are in custody or have been arrested.
Investigators say the Mexican Mafia was powerful enough to force rival street gangs to cooperate. Madrigal, described as a sort of regional manager, allegedly used a gang member in Ventura County, Edwin "Sporty" Moran as his outside man.
The investigation began with two shootings in April and a major heroin arrest, officials said. The operation was nicknamed Wicked Hand.
"We soon came to realize the incidents weren't happenstance," Ventura County Sheriff Geoff Dean said.
Authorities have not said where Madrigal is being held or why he is imprisoned.