The only fraud that I acknowledge is the 30,000 votes in Pennsylvania that the Post Office was ordered to deliver by the deadline and did not deliver until the next day.
I combine that, of course, with the Postmaster General's efforts to delay mail deliveries by destroying sorting machines, removing mail boxes, and other tactics. My own family suffered a $200 loss from these tactics when my husband's retirement business--online sales--was affected by a number of packages delivered after 5 weeks. I guess we were lucky, because other buyers had claims pending when the mail finally came through.
If we investigate anything, let's investigate the Post Office. After losing $200, I have absolutely no doubt that many votes never arrived on time.