There is a history of corpus-based approaches to the study of suicide notes in English going back to the 1950s. The classic book is "Clues to Suicide," by Edwin Shneidman and Norman Farberow. The next book-length study is by Antoon Leenaars (yes, two Os, two Es, and two As): "Suicide Notes: Predictive Clues and Patterns." There's also a really good review article, "Suicide Notes and Communications"--let me know if you want more information on it, as I unfortunately don't have the author's name handy and will have to hunt it down.
The most active researcher in this area today is John Pestian at CCHMC. You can reach him at jpestian at gmail.com.
-- K. B. Cohen Biomedical Text Mining Group Lead, Center for Computational Pharmacology and Lead Artificial Intelligence Engineer, The MITRE Corporation, Human Language Technology Division 303-916-2417 (cell) 303-377-9194 (home) http://compbio.uchsc.edu/Hunter_lab/Cohen