Ask and you will be given.
http://www.bfs.admin.ch/bfs/portal/d...en_zahlen.html
(especially "Freiheitsentzug - Insassenbestand am Stichtag")

and

http://www.bfs.admin.ch/bfs/portal/d.../19/03/03.html

What surprises me, in spite of what I wrote above, is the heavy share of those in "Untersuchungshaft". Sure, a good part of them will either get a fine or a "bedingte Haftstrafe auf Bewährung", but the time in U-Haft is something most of them will never forget.They will have it in clear memory even four decades later.

I was told that much of the crime-by-foreigners consists of robberies and theft by criminals who cross the border and escape back after the crime, counting on poor police coordination and difficulty of identification and extradition to get away with the crime.

As they say, you can rob one bank and get away with it. But to repeat the offence as a profession almost assures you will be caught eventually.

There are other issues: the inability to work of most asylum seekers and economic migrants means they are likely to resort to crime to survive. Asylum law was conceived out of guilt over the Holocaust and out of hostility to Communism and the Iron Curtain. It is unable to deal with massive flows of economic migrants enabled by modern communications. I remember the complaint of an immigration judge in the United States that he was well aware that only 15% of the asylum cases in front of him were genuine. The trouble was that he had no way of telling which 15% they were.

The Geneva 1951 Refugee Convention and the New York 1967 Protocol will be difficult to amend simply because in this postcolonial world there are now so many more sovereign states that will have a say. And few of them have any interest in making migration to the West more difficult. To some extent the issue of amending the European Convention on Human Rights and Fundamental Freedoms or domestic law implementing it (as the UK would like to do) is similar. The ECHR has 40 signatories (out of, I think, 46 countries in Europe; the absentee that comes notoriously to mind is Belarus which I know of as the country with unpublished laws, violation of which can put you in prison) http://conventions.coe.int/Treaty/en.../005-1-bis.htm and the EU also has a role, mandating respect of the Convention by its member states.

I suspect your first point is correct, which is one of the reasons for the public discussion about tightening up the borders. it is just simply not that hard for would-be-thieves to enter into the country without ever presenting papers at the border.

as to your second point - I don't think anyone will ever satisfactorily prove a direct causal relationship between poverty and crime, despite what Dickens might have written all those years ago.

It may be difficult to prove the direct relationship, but it is impossible to prove the contrary. And if you are poor and do not have enough money even for basic things, you may feel tempted to revert to illegal methods.

Necessity is the mother of invention - and thieves are very, very inventive.