Well, even though I've chosen not to deal with you guys; I also understand running a business can be very hard and thieves are undoubtedly some of the worst criminals there are...they aren't just stealing your items, they're stealing your time that you took to acquire those, whether it be through your own money and/or hard work. And as most can attest to, for most of us our "time" is quite valuable.
That being sad...and it can be hard to hear...but this sounds like textbook "inside" job. I don't mean to insult, it just happens statistically more than you might think...but it isn't your typical crack junky that knows to wear clothing to block video so that they could steal high end aftermarket parts they obviously knew was in those cars. Just something to consider.