Invincible thugs, burglars, killers
First, set up your own syndicate. Then go the staff screen and hire a thug. Next press the "Punish" button (red face at the end of the health bar) until it goes so far down it replenishes itself and will not go down from full. Find a bank with a full safe, equip your thug with a gun (preferably a machine gun), and rob the bank. Make sure your player moves out of the way as he/she will not be invincible. You can do this for any member of your own syndicate, except for yourself.