@robdean - Good post. Thanks for the additional professional insight. I have personally known several people who suicided, and in every case they exhibited regular bouts of depression and discussed how they "felt like ending it all" on numerous occasions to friends or associates.
It's true, there's the occasional personality who is totally secretive and doesn't divulge anything and suicides with no warning - but in the overwhelming majority of suicides, the warnings are there.