I’m sorry, but WTF is

We did not want to contact FlyCASS first as it appeared to be operated only by one person and we did not want to alarm them.

They are the company, running the thing. You are going to alarm them a whole lot more by going to the damn DHS. Like, I think DHS and TSA probably do need to know about this, but why not start with the actual intimately responsible party?

From what I can see, it looks like you have a SATA connector, though the power for it may need a special breakout, and an mSATA connector, both in the second photo