When Julie Day disappeared in San Francisco last Friday, her distraught family and friends promptly stepped in front of TV cameras and anxiously hung posters where she was last seen in an effort to stir up information about her whereabouts.

Then those close to her did something that may not seem novel in Silicon Valley, but which has helped them reach out to countless people to generate tips: they started an email campaign.

"A girl is missing who is a friend of mine," began one such email.

Day was last seen leaving a bar called the Bubble Lounge in San Francisco's Financial District. She was seen getting into a cab, apparently heading for a Bay Area Rapid Transit station to catch public transportation to her home in Walnut Creek.

In their search for her, Day's friends figured the Bubble Lounge and the surrounding business community have something in common--they are brimming over with young people who are connected to the Net.

"Different people we know socialize in San Francisco, and what do you do these days when you get to work? You get on your computer and plug in," said Keith McCardell, one of Day's friends, who shipped off an email about her disappearance to 50 people that was circulated to countless others in a matter of hours.

"I thought it was a great way to touch as many people as possible who might have been there," he added. "Some people have seen her, and there are other leads we've generated."

Email has long been pinpointed as one of the Net's "killer apps," with millions of messages continuously reaching the ever-growing online population. As a result, networks of friends and colleagues have developed that stretch beyond simply those who know each other directly. These networks pass information ranging from job openings to events among people with common frames of reference.

Some of the emails about Day have a poster attached so people can print and distribute it. The poster also can be found on a Web site dedicated to Day. Recipients are encouraged to call the Walnut Creek Police at (925) 943-5844 with any information.

Many organizations dedicated to tracking down missing children use the Web to publish pictures and details about disappearances and have solved some cases that way. The FBI uses a similar method to try to find fugitives.

In one of several recent examples, the Polly Klaas Foundation's Web site helped tracked down a little girl who was abducted in Santa Rosa, California, and taken to Mexico.

Someone who accessed the site saw the child's picture and alerted the authorities, said Jennifer Ugrin, a case worker at the foundation, which is named after a 12-year-old girl who, in 1993, was kidnapped at knifepoint from her bedroom in Petaluma, California, and later found murdered.

Although the National Center for Missing and Exploited Children ships posters via email to volunteers who promise to display them in a public place, Ugrin said using email to generate tips is a fairly new idea.

Online outreach may be even more imperative in the cases of missing adults, she noted.

"Some people are busy and working all day, and maybe they will only catch part of the news and are going to miss those short little clips. It would be easy to miss her story, because missing adults don't get a lot of attention," Ugrin said.

"The Net is really a powerful tool for anyone who has someone missing because so many people are connected that way," she added. "Having the flyer attached is a fabulous idea because someone saw her and knows what happened."

By Courtney Macavinta
Staff Writer, CNET News