Double votes.

A single state was found that there are handred thousands of double votes.  They may not necessary done by the voter themselves.  The voters might move out of that state.  Someone used their name to vote in this state.  Then who would have this information?  The insiders in the state government.  Those insider can pull the state database and fish those names, give them to someone of that party operatives to make fake double votes.  This was a team work.  Dirty team work.  If a voter is found having double votes by that person and it is verified by the signature,  it is a federate crime.