I would disagree with that premise, famously the FBI has used unpaid taxes to after a number of high profile criminals, most famously Al Capone but more frequently its gang members or fraud (like some of the Somali fraud cases in Minnesota). I believe they like to make your claim to encourage paying taxes, but practically they work together frequently. Crime shouldn't suddenly be ok if you pay taxes on it

> practically they work together frequently

Are the originators of these investigations the same? Might that matter?

> Crime shouldn't suddenly be ok if you pay taxes on it

Cool. Nobody is making that argument.