That's a good plan. Blessing someone is praying that God will consider them and see to their needs, including their need for justice under the law. If someone you know is a criminal, you should pray to God to be mindful of them and hear them. You should do that, instead of cursing them. Cursing someone would be more like praying that God would forget them and ignore them. If God forgets them and ignores them, they'll keep getting away with their sins, because God won't be watching. Bless them instead. Pray that their lives will be examined in the courts of Heaven, and that they will receive their rewards, every man according as his work shall be.