South American countries were largely neutral in World War II, and before it broke out were a common destination for Germans immigrating to colonies in Argentina and Brazil. Furthermore, there is a long history of German botany in Colombia that began the late 1800's. For these reasons, a German would not be so out of place in South America, nor would his connection to what was primarily a Eurasia-African and North American war particularly matter. Some anti-communist military governments prided themselves on the number of ex-Nazis in their ranks who helped with economic development when no one else would.

Furthermore, South America is rife with antisemitism that dates back to Spanish colonial times, when Freemasons and Jews were seen as threats to the state. The victory of Francoism in Spain was also significant, as former Viceroyalties looked to Spain for guidance in developing their nations, and Franco was quite pro-Nazi despite his "neutrality" in the war, and sent a battalion of Spanish volunteers to the Eastern Front to fight the USSR. Lastly, South America has a massive inland jungle, deserts and plateaus where it is very easy to be 'forgotten,' if you can brave the Amazonian wildlife. These rural regions were where colonies of former Nazis would gravitate, and do their best to shake off allegations of Nazism in order to life a normal life post-1945.

This is a good Wikipedia article on the subject.

http://en.wikipedia.org/wiki/Ratlines_(World_War_II_aftermath)

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Nazis in Argentina