I understand that the statutes of limitations for voter fraud can take up to 3 years !!!
Here is information on who you can contact about voter fraud you know about:
Complaints about ballot access problems or discrimination can be made directly to the Civil Rights Division’s Voting Section in Washington, D.C. at 1-800-253-3931 or by TTY at 1-877-267-8971.
https://www.justice.gov/usao-nh/pr/federal-election-fraud-fact-sheet