Nathaniel Rich writes in Harpers that he talked with the late David Sullivan, a California private investigator, about the state of the California prison system, which Sullivan

knew intimately from visiting clients for various murder cases he was investigating. He explained that the prisons have fallen under the control of the Mexican drug gangs, with the complicity of the guards, many of whom are Mexican nationals. But that’s a story for another time. [Remembering David Sullivan, October 15, 2013]

That would be a worthwhile story. The California Department of Corrections and Rehabilitation gives promotion points and extra pay for "bilingual" staff, which means staff who can speak Spanish. In a 2005(!) article called Spanish (Or An Immigration Moratorium) For Police Officers, I suggested that if police need Spanish-speakers, they will do better to teach regular Americans to speak Spanish than giving preferences to native speakers of Spanish.

"the English-speaking police can't learn Spanish that means that their departments will become controlled by Hispanic officers, which can lead to two problems; corruption, as seen in the Mexican police force; and disloyalty, expressed in an unwillingness to, for example, round up illegals. As far as corruption is concerned, we've already seen incidences of it. The point here is that corruption is endemic to Mexico, and that therefore, more Mexican-born officers will mean more corruption."

That's what Sullivan said is happening in California prisons.