The detective -- who once recorded an R&B single "Single Man" and was the grandson of legendary Harlem entertainer Willie Bryant -- was passionate about the industry and was familiar with even obscure rap artists. Soon, though, the music fan gave way to the police officer.

"I would recognize the artist and say, 'Wow, look at the guys he's going around with. Those are some bad dudes,'" Parker recalled. "So, I started to get to know everybody. ... I wanted to know what was going on in case I came across these guys and had to investigate them."

After Wallace's funeral went off without any problems, Parker became the go-to guy for rap-related investigations in the country's largest police force. By 1999, he and another detective were tapped to work on hip-hop full-time as part of the Gang Intelligence Unit. Parker coined an informal name for the pair, the Rap Intelligence Unit.

"We weren't officially Rap Intel," he said. "... They didn't want to make it like we were going after rappers, which we really weren't. I was just investigating all the problems they had."

Parker said that during the time he investigated hip-hop crimes, he shared the intelligence he gathered with police from Las Vegas, Los Angeles, Miami, Atlanta and New Orleans, as well as several New Jersey agencies and the FBI.

Officer Bobby Hernandez, spokesman for the Miami Beach police, said representatives from his department went to the NYPD first in 2001 for an informal training after disturbances on Memorial Day of that year.

"We recognized that we were getting a lot of rappers coming here, and we thought it would be a good idea to get some more information," he said. "... We wanted to be more hip-hop savvy. If we didn't do that, we would be irresponsible."

Miami Beach officers came back in 2003, when they received the 600-page binder. But Hernandez said the training was more important.

"They told us which groups had a criminal side and which did not," he said. "They told us, 'This guy is so pro-police, you don't even have to worry about him,' They told us, 'You don't even want to have this guy in your city.'"

Interest in crime, not lyrics

Parker said a police department collecting intelligence on rappers sounds more Orwellian than it is. It's the crime -- especially drug and gun possession -- that often goes with the hip-hop industry that he said police are interested in, not the lyrics.

However, civil-rights and free-speech advocates worry about law enforcement monitoring what entertainers say and possibly using their words against them. For example, in 1989, after N.W.A. released its protest song " -- -- -- tha Police," the FBI issued a bulletin to police warning that the song encouraged violence against them.

The NYCLU's Dunn said that in the world of rap, where most lyrics are based on braggadocio and fantasy, "It's a dangerous thing when police start assuming musical lyrics are evidence of criminal activity."

Will Griffin -- president and chief operating officer of Simmons Lathan Media Group, which produced the show "Hip-Hop Justice" for Court TV -- said he wants to help end "hip-hop profiling" because of the impact it has on young fans.

"We want them to believe in the system," he said. "We don't want them to think, 'Look at those guys, they are successful, and they didn't get a fair shake. What chance do I have?'"