Wikipedia is generally a good statring place for research:
http://en.wikipedia.org/wiki/Swastika
I've heard the reference to Native Americans before. I don't believe it is accurate, unless connected by migration of Asian people across the Pacific, estimated to have taken place around 20,000 years ago--neolithic period.
Follow a link or two within the main article to find out more about use of the swastica in the early 20th century, in different countries and cultures...
Definitely a symbol "ruined" by its Nazi use. Too bad, because it's simple, symmetrical, and high contrast; it really "grabs the eye" as a graphic.
David Parker