IIRC, the accident involved minor injuries and considerable property damage and the co-worker was briefly held by the German police. I don't remember if formal charges were filed.
If you carry two passports (let's say US and Italian), enter Italy on the Italian passport and try to return on the US passport, the first thing the DHS officer is going to look for is the Italy stamp in your US passport. Since you don't have one, you will likely have to answer a whole lot of unpleasant questions, at a minimum. With the exception of a couple of Israelis, the (few) people I know with “dual nationality” always travel overseas with their US passport.
That hasn't been my experience.I've done a fair amount of overseas travel since I got my Irish passport.I always use the Irish passport to enter a foreign country for two reasons...1)entering a member nation of the European Union with an Irish passport is a lot quicker and easier that using my US passport...plus,I think EU law requires me to do so but I'm not sure...and 2)when traveling elsewhere I fear (rightly or wrongly) that being identified as a US citizen in certain parts of the world is far more dangerous than being identified as an Irish citizen.
Also...I've never been given the least bit of hassle by US Immigration Agents when presented with my US passport that lacks any foreign visas.That doesn't mean it never happens...it just means that it's never happened to me.