Why is this case being tried in a court-martial?

As I read this article, the offense was committed off-base, albeit in the immediate vicinity. "Because of the nature of the offense, the Bernalillo County District Attorney’s Office ceded jurisdiction to the Air Force to conduct a further investigation and prosecute the case, according to the base press release." Why did the DA not prosecute? There seems to have been nothing peculiarly military about the charges.