Here is an article explaining the basics of suicide and why people choose it as an alternative to life, in the case of a Police Officer or NFL player, he may have been more driven by letting others down knowing this was unacceptable behavior he did not feel he had control over than to escape any type of accountability. In other words, he held himself accountable and gave himself the death penalty, an impulsive act not unlike the predatory nature of a mental problem.
http://www.kevinmd.com/blog/2010/06/6-reasons-people-commit-suicide.html