The Citywide Vandals Task Force arrested nearly 3,800 people 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 unit's 60 officers track and record aliases used in graffiti that are 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.
Most of the officers can decipher tags that, to the uninitiated, seem like scribbles.
"It's like another language; you just have to take the time to learn it," said Elwood Selover, commanding officer of the task force.
Graffiti have their own subculture. Generally, work is done by two groups: "bombers" and "writers." Bombers quickly paint simple messages, usually an alias, while writers take more time to make more elaborate, colorful work.
Writers choose a tag and rarely change it, even if they are arrested and end up in the NYPD database. They may spend hours leaving their mark in the most visible of locations, with subway cars being the ultimate prize.
"For the serious graffiti artists, who want to get out there and make their mark, the holy grail is still the subway train," said Lt. Michael Schaeffer. "That's kind of where it all started."
Most suspects arrested for graffiti in the city are teenage boys, and they come from all economic and ethnic backgrounds. "It's a mixed bag, honestly," Schaeffer said. "You have kids from good homes and good families doing this stuff, and their parents are beside themselves."
Schaeffer said the offense doesn't generally lead to more violent crime. However, the task force recently arrested two teenagers for gang-related graffiti and uncovered illegal handguns. Penalties can be increased if vandals write gang symbols, swastikas and other hate images in their graffiti.
An arrest and conviction may not deter graffiti writers, police said, because tagging after being convicted is considered a badge of honor.
And vanity also can be helpful to officers - many vandals these days videotape the act, set it to pumping club music, and post it on MySpace or Facebook.
"MySpace accounts do these guys in every time; it's incredible," Schaeffer said. "They just love to show it off."
Many consider graffiti art, and there are countless exhibitions. Writers like Fab 5 Freddy and Futura 2000 were underground heroes. The artist Jean Michel Basquiat famously got his start painting walls and went by the tag "SAMO."
Others say it's doesn't matter if it's pretty - it's defacement of property and illegal.
Jonathan Cohen, a former tagger who now runs a warehouse in Queens where it's legal to paint graffiti, said the older he gets, the more he sees both sides.
"I understand that people have businesses and are disgusted with it because it's on their property, but I also know it's an art form," he said.
Cohen thinks the penalties - which can include felonies with steep fines and jail time, depending on the amount of damage done - are too steep. "It's nowhere near the same level as robbing someone or killing someone," he said.
The task force was created in 2005 as part of an initiative by Mayor Michael Bloomberg that makes all graffiti investigations - including subway cars - now fall under one umbrella.
Arrests have risen every year since, along with complaints. Last year, there were 3,786 arrests, up from 2,962 in 2006. Complaints have doubled in that time, from 4,886 in 2006 to 8,866 last year, according to statistics.
Department Chief Ed Young attributes the spike to increased police presence on the crime. "When people are talking about it, they're going to notice it more, and report it more," he said.