That's not how it works. The police do the legwork, make the bust and do the investigation. The DA is the one who issues the warrants, does the plea bargaining, and sets the charges. I'm not saying the Sheriff couldn't have "queered" the investigation (using the old def of "queered", as in mucked it up, obfuscated the "facts"), but I know in our county if the above had happened, the case would have been moved to another county, to avoid the appearance of favoritism. This Sheriff is starting to smell...
Forgot to include: The Sheriff has nothing to do with the sentencing. That’s between the DA, the state laws, and the judge (who is unfortunately often the wild card).
That's what I was getting at. She works/worked for the county board of supervisors. He's the county sheriff. What relationship do they/did they have? What input could he have had in the sentencing process? The whole point is, he could very well be too close to perp's past to be involved now in this case. It should be looked in to. Whether it will or not is anyone's guess. I'm sensing (the FBI has now taken custody of the perp) the system is starting to close around the sheriff.
Also, this sheriff has been a very vocal opponent of the Arizona immigration law, stating publicly he wouldn't enforce it. The mayor of Tucson has also spoken publicly against the law. He's also a Democrat. Regardless of how your county functions, I see at least a semblance of political machine in Pima County, and wouldn't be surprised if the sheriff is protected politically.