The Probability of Hess Committing Suicide

The biggest puzzle is what motivation he would have to kill himself before being released. The suicide note itself is prima facia evidence of intent to commit suicide, absent evidence to the contrary or evidence of coercion. Couldn't this be as simple as someone even a typical non secret agent guard decided they wanted to take advantage of the opportunity to kill him? I could imagine this not even being a conspiracy until afterward with a cover up. There even could be a less grand conspiracy of any number of people and even intelligence personnel who maybe had for a long time kicked around the idea of killing him just because they hate Nazis too.