In order for Roger Barnett to avail himself of the protections offered in state code for a citizen's arrest, it's not necessary for Roger to have even specifically informed the illegal aliens, at the time of their detention, that he was arresting them. The detention itself was a de facto arrest.
But Roger should be made aware that if he is arrested, that his house will probably be searched, pursuant to that arrest, and you can bet they will take his computer hard drive as possibly containing "evidence". His HD will contain all the names and addresses of everyone else involved with Roger in regards to protecting the border. It will also include information about what Roger and others are doing, have done are and planning to do. Even if the search is later tossed on 4th Amendment grounds and the HD returned, all that info will remain in the hands of the feds. Bad news. In fact, this may be what is really behind the arrest in the first place.
First, make a back up of all critical user data files on a CD-RW and put that someplace "very secure". Second, re-route the power and data cables for the hard drive through the side of the computer so that your HD is now outside your computer and in plain sight. Place a large hammer next to the HD. When they come through the door, administer several severe whacks to the HD. Replacement HD's can be had for $100. After they've left, reload the new HD with your program disks and then your CD-RW backup disk containing your user files and you're back in business. Pain in the neck? Yes, but better than the alternative.
The Army uses thermite pyrotechnics to accomplish the same thing, but wives get real fussy about the use of such devices inside the house. Go figure.
Regards,
Boot Hill