Graffiti artists come to New York City from all over the world to leave their mark on subway cars, buildings and billboards. They will spend hours surveying and then spray-painting hard-to-reach spaces with remarkable precision.
The finished product may be impressive, but it's also illegal -- and constantly being monitored by a specialized New York Police Department graffiti unit.
NYPD Graffiti Arrests Up 28 Percent
The unit is sophisticated in its own right, keeping a database of offenders and holding weekly meetings to pore over graffiti crime stats.
Called the Citywide Vandals Task Force, the unit arrested 3,786 individuals last year, up from 2,962 in 2006. They have made several high-profile arrests this year, including one Tuesday, when a teen was accused of defacing a mural dedicated to Sept. 11 victims.
The 60 officers in the unit track and record the aliases used when writing graffiti, known as "tags." A searchable database has more than 8,000 entries, allowing the task force to track active writers and cross-reference their tags after an arrest to possibly add charges if a tag is found in more than one location.