I have no idea whether or not she is guilty, or indeed whether anyone in a position of power in the Ukraine is entirely innocent. That isn't the subject of this blogpost.
My point is one of which her story is an example. If a nation's electoral winners routinely prosecute former leaders, truly representative elective government is likely to vanish.
Who is willing to face possibly losing a real election if that outcome will be followed by exile or a (probably dishonest) prosecution and prison? Short answer: no sane person.
The result of such policies is the degeneration of elective government into sham elected government, where the opposition is allowed no access to the media, its candidates are harassed or barred from running, and the same president or PM is always reelected, as in Venezuela. That, or outright one party rule a la China or North Korea.
It is the reason the ICC indictments against Libya's Gaddafi are a problem. He cannot step down and remain in Libya without being tried by his own people, and cannot leave without being tried by the International Criminal Court in the Hague.
We have boxed Gaddafi into a corner where his only alternative is to stay in Tripoli and fight it out to the bloody end; an end where most of the blood shed won't be his. If the goal was to get him out of the country and stop the war, the indictments feel good but weren't smart.