Police and prosecutors say they are concerned that a Web site claiming to identify more than 4,000 informants and undercover agents will cripple investigations and hang targets on witnesses.
The Web site, WhosaRat.com, first caught the attention of authorities after a Massachusetts man put it online and named a few dozen people as turncoats in 2004. Since then, it has grown into a clearinghouse for mug shots, court papers and rumors.
Federal prosecutors say the site was set up to encourage violence, and federal judges around the country were recently warned that witnesses in their courtrooms could be profiled online.
"My concern is making sure cooperators are adequately protected from retaliation," said Chief Judge Thomas Hogan, who alerted other judges in Washington's federal courthouse.
The Web site is the latest public effort to identify witnesses or discourage helping police. "Stop Snitching" T-shirts have been sold in cities around the country and popular hip-hop lyrics disparage people who help police.
Such tactics hinder police, said Ronald Teachman, police chief in New Bedford, Mass.
"These kids have the idea that the worst offense they can commit is to cooperate with the police," Teachman said.
Sean Bucci, a former Boston disc jockey, set up WhosaRat.com after federal prosecutors accused him of selling marijuana in bulk from his house. Bucci is under house arrest awaiting trial and could not be reached, but a WhosaRat spokesman identifying himself as Anthony Capone said the site is a resource for defendants and does not condone violence.
"If people got hurt or killed, it's kind of on them. They knew the dangers of becoming an informant," Capone said. " If they decide to become an informant, with or without the Web site, that's a possibility."