No offense intended, and towards you least of all, but holding criminal proceedings in foreign countries is a failing endeavor and a concept I am very familiar with. Completely leaving aside national bias, such prosecutions place an enormous burden on domestic prosecutors and it is no stretch to say that, even in the best circumstances, a trial cannot be as effectively heard or adjudicated in a country foreign to where the crime was committed, the victims are located and the evidence is most readily found.
Mexico also claims it will prosecute Mexican citizens under Article IV of our Extradition Treaty with them when they refuse extradition and the result is almost always that the trial never moves forward, the defendant is acquitted, or the sentence is a very small fraction of what a conviction would have led to in a US court. Your anecdotal news story aside (and Mexico also has exceptional cases where justice works) it's hardly unfair to expect that, even in Brazil, such procedures are a very poor substitute for a functioning extradition agreement. More problematic is the fact that, if a foreign national is found non-guilty in a foreign prosecution of a US criminal case, the criminal in question can, in many cases, then come back to the United States, or at least travel internationally, and be immune from further US prosecution under "double jeopardy" laws.
I don't disagree that Brazil, like the US, is a sovereign nation that has the rights to make any laws it chooses to (just like Darfur), but it is the substance and effectiveness of those laws that deserves respect (or not as the case may be.) All systems of justice, sovereign or not, are not equally worthy of respect.
..and Italy actually does have an
extradition treaty with the US that allows extradition of Italian nationals (and vice versa.)