This reminds me of the grad student friend of Pepper White (The Idea Factory) who killed herself in her car by asphyxiation.
I knew an MIT undergraduate who committed suicide in his dorm room. I didn't know him very well, however. He lived in Next House. I saw him occasionally when I ate in the Next House dining hall. He didn't say much, but when he spoke it was usually some cynical comment. No one who knew him thought he was suicidal.