San Bernardino (Calif.) Police Sgt. Dwight Waldo, one of law enforcement's foremost graffiti enforcement investigators, discusses the five types of graffiti, explains how to gather intel to identify messages, and tells patrol officers what they need to include in a vandalism report. Sgt. Waldo's book, "Taggers and the Graffiti Culture," is proprietary training material. To reach Sgt. Waldo, send an e-mail to email@example.com with "graffiti" in the Subject Line.