Was Heidegger a Nazi?

Heidegger, according to Wikipedia, joined the Nazi Party ten days after being elected as rector of University of Freiburg. Although the Nazi party was originally formed as a fascist socialist party, the party's intent was to limit party membership to less than ten percent of the general population. Business and government elites were encouraged to join, the general population was not. Party membership was forbidden to those who served as soldiers in the army, however for the elites (the SS, for eg) party membership was required. Although government workers and bureaucrats comprised only five percent of the general population, they made up fifteen percent of the party membership.
Bureaucrats (including university rectors, I assume) were three times more likely (than the general German population) to join the Nazi party. It is wrong, however, to extrapolate that government workers and bureaucrats were therefore three times more likely to support the Nazis.

Heidegger came to prominence when philosophers still held a position of prominence in university politics and governance. Being offered a rectorship of a major university was a great honour; it afforded a level of stature and respect granted to only the best and brightest.

Heidegger joined the Nazi party ten days after being elected rector - and resigned the rectorship one year later. Hannah Arendt, a Jew and  considered one the most important political theorists of our time, was a long-time romantic partner. At the end of the war, Heidegger was judged to be a follower of the Nazi party, not an active participant. He never spoke about the war and his time as rector, other than to say that it was the stupidest thing he had ever done. He did, however, have this to say about the mechanization of agriculture:

Agriculture is now a motorized food-industry — in essence, the same as the manufacturing of corpses in gas chambers and extermination camps, the same as the blockading and starving of nations, the same as the manufacture of hydrogen bombs.

This statement echoes the thought of sociologist Max Weber, an earlier Freiburg professor. Weber developed the theory of social mechanization link The horrors of the holocaust were only possible through bureaucratic and industrial efficiency. The statement above expresses disgust at the mechanization and dehumanization of war, it does not  express indifference to the horrors of the holocaust.

Heidegger is guilty of ambition and perhaps temporary hubris. His silence on the subject of WWII cannot be seen as support for the ideals of national socialism and the Nazi Party.