Cop: A True Story - Sgt. Michael L. Middleton
Former Sargent for the LAPD, it chronicles the lives of radio car officers (the ones you see the most) from about the late '60's to his retirement in 1988. It's a revised edition so I'm sure there will be some more updated stories and information, because a lot has changed in the last 22 years.
It forms an interesting contrast to my other book,
Homicide: Life on the Killing Streets, which is about the Homicide Department in Baltimore in the late '80's. The uniform officers (officers in Uniform and radio cars) are just called "Uniforms" and aren't treated with much respect or expected to be competent. It's a little bit of an arrogant and elitist idea presented, but the radio car patrol officers are the front line soldiers, and considering EVERYONE who wants to be out in the field doing police work has to do patrol, I figured this would be a good book for me.