NCIS would have to be involved in this. Erin Corwin is a military spouse. SWs have been issued for quarters on a MC base. Two men possibly involved are Marines. The Marines have ordered JC not to give public statements as per his CO. I'm sure they are very much part of this investigation.
On a side note: I've have many an occasion to go onto a MC base. Every time the gate has been manned, and 100% ID is required. Not just for the driver, but for the passenger as well. Those with DOD stickers get waved through, those without have to show ID. (Military ID and/or Driver's License.) No one cares who goes off base, that side is not manned with MP's or Civilian Security Guards. (Which was the case for a couple of years when those jobs were outsourced, but as of June, it was MPs manning the gates again at the MC installation I was on.)
On some Navy bases, you are required to get a written permit to enter the base with the dates you intend to be there. You have to display it every time you go on or off the base.
This is all my own personal experience.