The man, 35, had reportedly lived illegally in Austria since 2004, and would only have had to wait until midnight last night to cross freely into Slovenia, which joined Schengen along with eight other countries.
The other countries to free up their borders to internal passport-free travel were the Czech Republic, Hungary, Poland, Slovakia, Estonia, Latvia, Lithuania, and Malta.
The newly-expanded Schengen area stretches over 24 countries, home to a total of 400 million people, more than the population of the United States.
The zone now covers much of the European Union, as well as non-EU members Norway and Iceland. The United Kingdom and Ireland have opted out of the agreement, and new EU members Romania and Bulgaria have yet to meet security requirements to join the zone.
