Criminals who got trained and became, say, CIA agents or FBI or soldiers of war.
Given how many ordinary non-criminal and non-violent men, and sometimes women, of all types tend to enter these life threatening, human enemy battling to death professions, VOLUNTARILY, is that really a good and effective way to punish some criminals instead of jail or a death sentence, and in some war related times, battle fronts, as in, there instead of a jail or a death sentence, but why would even LESS than stellar governments want downright BAD people to end up as heroes of any kind?
Then again, how do good people in the Army or the FBI or the CIA imagine themselves getting ALONG with someone or working with someone who is or was a violent criminal guilty of a serious crime?