I don’t have the files yet, but I should ask for backup copies, previous versions?
“I don’t have the files yet, but I should ask for backup copies, previous versions?”
Won’t do any good. Anything they “give” you can be faked. Aside from the wayback machine, you would have to have access to the PC itself that they developed the website on AND have someone perform a forensic analysis on it, AND that PC would have to be obtained BEFORE they knew what you were up to so they couldn’t cover their tracks on the PC before they handed it over to you.
With a hex editor, you can compare file contents.
http://www.flexhex.com/docs/howtos/file-comparison.phtml