to campaign donations...just ask former V/P. Mike Pence (see link)...if someone believes they have probable cause under Indiana law (or lack thereof ;-)) to investigate Mayor Pete, I say "go for it".
Meanwhile, back to DJT...IMO there's more than enough probable cause to indict him on fraud and tax evasion...then let the judicial process play out.
Link: https://mediaschool.indiana.edu/news-events/news/item.html?n=corporate-cash-helps-fill-indiana-politicians-coffers