When the election tally is announced its usually too late. Hence, my emphasis on actions we can take to PREVENT vote fraud. For example, in the 2000 election I prevented over 100 fraudulent votes out of 850 cast at the precinct where I worked. That’s a significant percentage.
How did you do it? In all the years I've worked, I can only think of 3 times that I prevented someone from voting who shouldn't.
One was a water referendum and a man came in an announced in broken English that he was not a citizen. (I was a poll watcher in that election). The ladies at the table discussed it among themselves and said, "He's lived here 25 years, he should vote." They were getting ready to register him when I called the election judge in from the back room and she told the women that he wasn't eligible to vote.
Two was a teen ager who wanted to vote in his brother's name. I happened to know the boys. They were Muslim, as was their father, and they were all named Muhammad -- but one was not registered. I sent him home for his ID. (He didn't come back until the next election.) I got scolded by a friend of mine for turning him away because she thought that he'd vote for our candidate -- I wasn't so sure. And even so, he wasn't eligible unless he came back and registered properly. His mother is an attorney, and I know she'd tell him the same thing.
Three -- a mom asked if her daughter who was home from school could vote. I told her she could and told her what ID she needed. A half hour later the girl came in with the proper ID and I noticed that some of her papers said, "Madison". I asked her if she'd already voted in this election, and she said "Yes, in Madison". I told her that she couldn't vote twice in the same election and turned her away.
That's not many "saves" for years of work, but it's worth it. Of course, in Milwaukee and in Madison they are registering more people than live in a building all the time. Because we register new voters at the polls (a stupid idea IMO) we have no way to check if they are really telling the truth. After every election they send out postcards to the new registrants and about half of them are returned as bad addresses.