Robert Horan, the chief prosecutor of Fairfax County, Va., could hardly believe his eyes last December when he logged onto his office computer and read the front-page article on The New York Times site.
The story quoted anonymous law-enforcement officials implicating teenager John Lee Malvo as the triggerman in a series of sniper shootings that terrorized the Washington D.C. area last fall.
Mr. Horan called a press conference that day and denounced the article and the anonymous sources who leaked it as "dead wrong." As The New York Times admitted this month, it wasn't Horan who was mistaken but rather a reporter, Jayson Blair, who apparently fabricated the evidence that Malvo was the shooter, including the unnamed sources.
Such is the power of frequent leaks shared among prosecutors, police officers, and journalists that some reporters were more inclined to believe Mr. Blair's fictitious account than a prosecutor's denials. As a result of this symbiotic relationship, gossip by law-enforcement officials passed along to reporters can become front-page news.
Unfortunately, say legal and journalism ethicists, neither leakers nor the news outlets that rely on them give enough thought to the harm leaks can cause to investigations as well as the rights of defendants and victims.
Lawyers' ethical codes and agency regulations strictly limit what investigators are allowed to say about ongoing cases. Violators can lose their jobs or even be prosecuted themselves. In the most extreme circumstances, such disclosures can also result in criminal charges being dropped against a suspect.
Still, such penalties don't stop leaks. Often, it's those on the sidelines of a case - rather than those actually investigating the crime - who leak information, says Carl Stern, who covered the Justice Department for NBC News before serving as spokesman for former Attorney General Janet Reno. Those not involved may massage their bruised egos by feeding rumors to reporters.
"Everyone likes to feel they're in the know," says Mr. Stern, who now teaches public affairs at George Washington University in Washington.
But police or prosecutors in charge of an investigation may also purposely leak information. They may tell reporters about a confession to reassure the public that they've caught the actual perpetrator, says Jane Kirtley, professor of media ethics and law at the University of Minnesota. Or, she says, they might want to throw off a suspect by releasing word that he's not being investigated.
Investigators also fish for evidence to support their theory of a case by sharing details with reporters, says Randy Dyer, an attorney in Salt Lake City who represents the family of Elizabeth Smart, the teenager abducted from her home last year and rescued in March.
Mr. Dyer says that desire to unearth evidence for investigators' novel theory may explain why Salt Lake City law-enforcement officials shared details about the Smart case with two reporters they'd met while they were working on security for the 2002 Winter Olympics.
The investigators floated their suspicion that Smart's family had a role in her disappearance, says Dyer. "They were hoping they'd shake the tree and see what would fall off - if anything would corroborate their theory," he says.
The theory turned out to be false, and the reporters were fired by the Salt Lake Tribune for sharing the law-enforcement leaks with the National Enquirer in exchange for $10,000 apiece.
Dyer says no one involved gave enough thought to the leak's potential impact on the Smart family. "They were victimized by these false, salacious reports," he says. "It was embarrassing and humiliating to read."
Not all law-enforcement officials agree about the benefits of strategic leaking. Horan says he can't think of an instance in his 35 years as a prosecutor in which strategically leaking information to a reporter wound up helping his case.
In fact, leaks are more likely to compromise investigations, says Thomas DiBiagio, the US Attorney for Maryland. Leaks can limit police surveillance options by alerting suspects to the fact that they're targets, Mr. DiBiagio says. A suspect will be wary about talking on the phone or confessing to friends, who might be wired by police.
Leaks after a suspect is indicted can make prosecuting them more difficult. "It makes it harder to get a fair and impartial jury," DiBiagio said during an interview last week in his Baltimore office.
It's also hard for truthful law-enforcement officials to get the benefit of the doubt from journalists reporting on leaks. And on the flip side, professor Kirtley says, journalists have to be careful about using their law-enforcement sources and the information they provide. "Almost invariably, a source demanding confidentiality has an agenda," Kirtley says. "You have to ask what this means for my readers and viewers."