Graffiti has been around since ancient times. There is graffiti in the ruins of Pompeii. However, for the purposes of a modern graffiti investigator, you should have a grasp of graffiti from the 1970's and forward.

One of the leading researchers on modern graffiti is Vancouver BC Police Sergeant Valerie Spicer. An important theme of her work is that graffiti is a gateway crime. The following is the abstract from her master's thesis, which is available online:

In the 1970s, a new form of graffiti emerged. By the mid 1980s it had surfaced in other urban centers. This new phenomenon, referred to as Hip Hop graffiti, has been documented in a variety of forms, but aggregate studies remain sparse. While there are valid arguments that justify the artistic merit of graffiti, there are also negative implications experienced by this subculture's lesser known participants. Visual assumptions of graffiti can misconstrue an act of intentional vandalism as an artistic attempt. This dataset uses information on 536 individuals who engage in graffiti in Vancouver. This information was obtained through the Vancouver Police Department for the period between January 2001 and December 2004. Analysis shows that repeat graffiti offenders commit more violent offences, have more criminal charges and have stronger associations to the subculture. Policy implications are discussed and solutions for this problem are proposed.

Originated in NYC in the 1970s as part of hip hop culture.

The four pillars of hip hop are rapping, DJing, breakdancing and graffiti writing. I have seen first hand that these four activities have a strong connection. In researching graffiti, I attended a graffiti contest at a free wall in 2011. While the artists were creating murals, the audience was entertained by people break dancing to the beats of a rapper and a DJ.

Anybody can pick up a spray can and make a passable tag, but doing the other hip hop artistic endeavors are much more difficult. So there are vastly more graffiti writers than rappers, DJs and break dancers. Many novice graffiti vandals are unaware of their hobby's relationship with hip hop.

The first graffiti celebrity was Taki 183 in New York City in the early 1970's. His name was a portmanteau of Demetraki (his first name) and 183rd Street (where he lived). An anonymous teenager is credited with starting a worldwide movement that forty years later causes billions of dollars of damage. In 1985 a major motion picture inspired by TAKI 183 called Turk 182 was released. The film featured Timothy Hutton playing a plucky insurgent graffiti artist fighting a corrupt city hall.

New York City remains the center of the graffiti world. NYPD has countered this with the Citywide Vandals Task Force, commonly known as the Vandal Squad.

Today, most big cities in the the Unites States have at least one graffiti investigator.

In 2010 the Seattle City Auditor issued a report with recommendations on how the the City should deal with graffiti. One of the recommendations was that there should be a full time graffiti detective. This led to the creation of my position.