Suppose a person has been convicted of murder. He did it. He bribes witnesses and manufactures evidence to clear himself while in jail. How do you say this in one word or phrase? It's as simple as:
The thesaurus entries for 'exonerate' (like 'absolve' or 'exculpate') all seem to lean towards innocence. An answer doesn't have to be formal or informal; anything where you don't have to explicitly specify 'false' and 'not found guilty'.