Just found something interesting in one of the court documents regarding Paul Manafort, Specifically in the 'Defendants Motion To Dismiss".
https://www.courthousenews.com/wp-content/uploads/2018/03/manafort-dismiss-march-27.pdf
If you look at the end of page 23 and the beginning of page 24 of the PDF, it clearly states that Manafort had ALREADY been investigated by the DOJ for these same charges in July of 2014 (Manafort voluntarily showed up at that time, by the way).