That's simple: Hispanics are counted as white in the prison population and nonwhite in the victim stats. So if a Mexican is convicted of beating his Mexican wife, then it comes out in statistics as a "white" on "nonwhite" crime.
Hispanics are white if they come from Spain. Mexicans are often a combination of white and Indian.
Race is really nothing more than a culture issue.
In memory of Ahmed Merabet, Rafael Ramos, and Wenjian Liu.