Our group, the Badge of Life program, just completed an exhaustive study of police suicides that covered all 50 states during 2008. A summary of our findings, as well as the case-by-case suicides themselves, can be found at
http://www.policesuicidestudy.com/
Suicides were gathered through a web-based, year-long surveillance of news reports on police suicide. We reviewed approximately 119,000 suicide-related articles during the year, captured as much information as we could from each, and formed our conclusion--which we feel are verifiable and supported by past research and CDC/NOMS data.
We found there were 141 police suicides in 2008. Before saying "That's too low," look at our methodology. Indeed, our conclusions do take the wind out of some of the totally unverifiable numbers that have been floating around the community, some as high as 450 per hear.
For those who like comparisons, the 141 suicides is well over twice the number of officers killed each year by felons. It represents a suicide every 2.5 days.