This might require a deal with a welfare-state like Sweden, though with +180 countries to choose from, this might not be a problem.
Perhaps our problem with crime and prison is that we haven't figured out what we want to do with convicts. Are they evil-doers to be punished? Are they the product
of environment? Are they just plain incorrigible?
Let's find out.
Let's say we have 900 convicted armed robbers.
The first 300 will have to account for their crimes. Now these can be subdivided.
The first 100 will get the typical prison sentence--though more punishing--let's say breaking rocks or doing some other hard, largely useless, activity at a loss of +$25 000 per year to the taxpayer.
100 will have their right arms chopped off--with anesthesia and anteseptic. They are then fitted with plastic arms, set free, maybe with some welfare and their ability to hurt again diminished.
100 will have to restitute their victims. Refusal will mean they lose a kidney to be sold in the open markets to restitute victims. Then they are set free.
Recidivism rates will be analyzed
For the next 300, there will be a district. It will be 20 km wide and 20 km long, with a +30 meter wall with towers etc.
Costs should be lower due to low perimeter-to-surface ratio (It's easier to watch over 10 000 in one place than groups of 100, each in 100 places).
Within this district, convicts rule. Anyone can enter, but only-non-convicts can exit. Each convict will be given a small allowance to live on. If he wants more, he can work, deal, etc.
As with migration, convicts can buy what they want--supplies, food, cigarettes, booze, carpets, furniture, records, etc. Goods can also leave the district.
As for the last 300 convicts, they can go to a country where the environmental theory of crime holds sway. With some subsidies, they will be rehibilitated and released. Mind you, it will be in a society where there is no TV violence, fat-taxes, rap music in some Scandanavian language extolling good behaviour, high tariffs on American cars, etc.
Again, recidivism rates are to be analyzed.