In London, a fifth of all offences, a third of all sex attacks and half of all frauds are committed by those born overseas.
But as we shall see, this is not only extraordinarily complicated and time-consuming, it is very often doomed to failure. In the year to April, Britain received more than 3,500 requests from foreign countries for the return of their criminals.
More than 150 were suspected or convicted murderers.
So why does our extradition system take so long to send back the suspected foreign criminals found here?
And what are the implications for our own safety as rapists and murderers freely walk our streets?
For as one London senior police officer told me: 'A criminal doesn't stop being a criminal just because he moves country - and that is the real problem.