Today I've read in 'Journey into the Whirlwind' by Eugenia Ginzburg, that prisoners in the USSR could be re-sentenced. They had been accused and found guilty of a crime (usually counter-revolutionary behavior), and already received a certain prison sentence (let's say five years). Later, when the Soviet government deemed these crimes worthy of a stricter punishment, they re-tried the prisoners to give them a longer sentence (let's say ten years).
Sometimes I find modern day examples of people having been found guilty being exonerated, since the law has become less strict on a certain issue (possession of marijuana for example). They're still guilty of whatever they did, but the sentence is less harsh. However, this is the first time I've read of a law becoming more harsh, and people being punished harder for the same crime they were already (being) sentenced for. Are there more historical examples of this?
Short disclaimer: I am not looking for people being retried because of new evidence or witnesses, or receiving a different sentence after an appeal. It's the exact same crime, the same ruling (guilty), only the punishment is harsher.