Two weeks after Joshua Lipton was charged in a drunken driving crash that seriously injured a woman, the 20-year-old college junior attended a Halloween party dressed as a prisoner. Pictures from the party showed him in a black-and-white striped shirt and an orange jumpsuit labeled "Jail Bird."

In the age of the Internet, it might not be hard to guess what happened to those pictures: Someone posted them on the social networking site Facebook. And that offered remarkable evidence for Jay Sullivan, the prosecutor handling Lipton's drunken-driving case.

Sullivan used the pictures to paint Lipton as an unrepentant partier who lived it up while his victim recovered in the hospital. A judge agreed, calling the pictures depraved when sentencing Lipton to two years in prison.

Online hangouts like Facebook and MySpace have offered crime-solving help to detectives and become a resource for employers vetting job applicants. Now the sites are proving fruitful for prosecutors, who have used damaging Internet photos of defendants to cast doubt on their character during sentencing hearings.

"Social networking sites are just another way that people say things or do things that come back and haunt them," said Phil Malone, director of the cyberlaw clinic at Harvard Law School's Berkman Center for Internet & Society. "The things that people say online or leave online are pretty permanent."

The pictures, when shown at sentencing, not only embarrass defendants but also can make it harder for them to convince a judge that they're remorseful or that their drunken behavior was an aberration. (Of course, the sites are also valuable for defense lawyers looking to dig up dirt to undercut the credibility of a star prosecution witness.)

Prosecutors do not appear to be scouring networking sites while preparing for every sentencing, even though telling photos of criminal defendants are sometimes available in plain sight and accessible under a person's real name. But in cases where they've had reason to suspect incriminating pictures online, or have been tipped off to a particular person's MySpace or Facebook page, the sites have yielded critical character evidence.

"It's not possible to do it in every case," said Darryl Perlin, a senior prosecutor in Santa Barbara County. "But certain cases, it does become relevant."

Perlin said he was willing to recommend probation for Lara Buys for a drunken driving crash that killed her passenger last year - until he thought to check her MySpace page while preparing for sentencing.

The page featured photos of Buys - taken after the crash but before sentencing - holding a glass of wine as well as joking comments about drinking. Perlin used the photos to argue for a jail sentence instead of probation, and Buys, then 22, got two years in prison.

"Pending sentencing, you should be going to (Alcoholics Anonymous), you should be in therapy, you should be in a program to learn to deal with drinking and driving," Perlin said. "She was doing nothing other than having a good old time."

Santa Barbara defense lawyer Steve Balash said the day he met his client Jessica Binkerd, a recent college graduate charged with a fatal drunken driving crash, he asked if she had a MySpace page. When she said yes, he told her to take it down because he figured it might have pictures that cast her in a bad light.

But she didn't remove the page. And right before Binkerd was sentenced in January 2007, the attorney said he was "blindsided" by a presentencing report from prosecutors that featured photos posted on MySpace after the crash.

One showed Binkerd holding a beer bottle. Others had her wearing a shirt advertising tequila and a belt bearing plastic shot glasses.

Binkerd wasn't doing anything illegal, but Balash said the photos hurt her anyway. She was given more than five years in prison, although the sentence was later shortened for unrelated reasons.

"When you take those pictures like that, it's a hell of an impact," he said.