Remember the Tom Delay indictment? Delay tried desperately to get the whole matter decided before the election, and it's STILL languishing in the Texas appeals courts.
Jon Tester beat Conrad Burns in the Montana Senate race in 2006 by 3,562 votes. Burns was under a legal cloud at the time of the election, but was later cleared—probably he would have been re-elected if not for that, and the ‘Rats would not have captured the Senate.