I guess they were hired because they could speak Spanish well.
Actually that's true. But only part of the story.
Hispanics are given preferences for Federal jobs. Some states prohibit this, but not the federal government. So people who come from another country, who have no history or claim of individual discrimination or victimization in this country, are given preference over the native born.
It gets better. Hispanics - mostly Mexicans of course - are preferred in the BP job because it shows "sensitivity" to the illegal aliens barging the border. Wouldn't want to make them feel bad about themselves by having to confront angry Crackers from Georgia with guns, would we? That would be soooooooo Un-PC, and that's a big no-no in modern America.
And of course, being from Mexico, they bring all the bagagge of their home country and culture....like the quaint traditions of Mordida, where getting a job as a policeman and then accepting bribes for looking the other way is considered quite normal.
And who knows? Maybe they did this when they lived in Mexico. There are no central databases on people like there are in the United States; arrest records are sketchy to non-existent. For a price, they disappear. These guys could have been sent up to the U.S. for precisely the reason of getting jobs in the BP after naturalization: Moles.
The new America, a lot like Old Mexico.