A U.S. Justice Department study found that graffiti discourages people from using mass transit, makes business districts less attractive to shoppers and increases fear of gangs among residents. Law enforcement and community officials talk about how graffiti —usually spray-painted or applied with indelible markers— is costly in terms of removal, lowered property values and lost business. Graffiti Tracker is a web-based system designed to help identify and prosecute graffiti vandals.