It's not as if apprehending an evil mass murderer and putting him on trial would have been unprecedented, with all sorts of insurmountable logistical problems. It's actually been done before. For example, 50 years ago, the entire world watched as former SS officer Adolf Eichmann was put on trial in Israel for his role in organizing mass deportations of Jews to death camps in German-occupied Eastern Europe during World War II.

Wasn't that a better way to bring this murderer to "justice" than if the Mossad agents had just executed Eichmann on the spot in Argentina?
Another effort to bring a mass murderer to trial ultimately failed, to the disappointment of many, when Augusto Pinochet died of natural causes in 2006. Pinochet led a military overthrow of the democratically-elected government of his native Chile in 1973. On September 11 of that year (the same date on which New York and Washington would later be attacked in 2001), the Chilean military bombed and strafed La Moneda, their equivalent of the White House, as part of their coup. Thousands of citizens were rounded up, tortured, and killed, as was vividly portrayed in Costa-Gavras' 1982 film Missing. When Pinochet finally yielded power in 1990, he ensured that an amnesty law was in place to shield him from future prosecution, but the Chilean justice system was in the process of removing that amnesty and bringing Pinochet to trial for his crimes when he died. The families of his victims felt robbed of their chance to see the man who ordered the deaths of their loved ones brought to justice.
Sadly, the families of the victims of the September 11, 2001 attacks have also been robbed of a chance to see Osama bin Laden brought to trial. Instead, we have the United States setting an example that vigilante justice and extrajudicial killings are acceptable.
I'm deeply disappointed that President Obama, a former lecturer in constitutional law, doesn't see this difference.