The only way you can prove that either way is to reveal the source code.
It may be a lie, it may not be.
You can't prove a negative.
That code is proprietary.
As it turns out, back in 2004? Yeah, Diebold was manipulating votes, we know this from a whistle blower. . whom they then prosecuted for revealing that fact. This, of course, sent out a clear signal for anyone else who would dare to blow the whistle on any corruption.
So? Since it happened once, and this is for all the marbles, of course it can happen again. Stop being so obtuse.
Whistleblower Charged With Three Felonies for Exposing Diebold's Crimes
www.huffpost.com