I am deeply sorry for your experience and I totally understand that it triggers something, but let's be ice cold logical for a moment.
If there is no evidence of a crime, you cannot prosecute someone in a constitutional democracy.
If you could you could just make up any claims and get rid of people you simply despise.
Which happens in various regimes...
So although it's certainly a possibility that such cases happened, as long as there is no evidence that they happened, they didn't for all legal matters.
We are discussing the pardon power, an explicitly anti-democratic measure that is unilateral and unreviewable. The constitution defines a federal republic, not a democracy.
If there is no evidence of a crime, you cannot prosecute someone in a constitutional democracy.
If you could you could just make up any claims and get rid of people you simply despise.
Which happens in various regimes...
So although it's certainly a possibility that such cases happened, as long as there is no evidence that they happened, they didn't for all legal matters.