Before she disappeared from a Richmond university four weeks ago, Taylor Marie Behl recorded her moods, her crushes, her insecurities in 50 entries she posted online over the span of 12 months. In language both spare and pensive, she detailed rites of passage, from earning her driver's license to preparing for university.

With her chronicles, Behl, 17, of Vienna gained entry into a vast virtual community, a very public arena in which her writings were there for anyone to see at any time, a personal diary with no key.

Now police also are privy to the disagreements that Behl had with her parents, her emotions on any given day, even her sexual exploits. By combing through the missing student's online journal and profiles, they learned not only about her favorite musicians and movies but also about the many people with whom she was acquainted on the Internet -- users with such online identities as "Citizen Cope" and "Chaos."

Behl's online musings have served as a portal into her world, a priceless resource for those investigating her disappearance from Virginia Commonwealth University. Because these days, when someone goes missing or becomes a crime victim, the police not only search the person's home and phone records for clues, they also scour cyberspace.

The Internet, police said, has emerged as a virtual tip machine that often maps the course of an investigation. Within seconds, detectives are able to amass a great deal of information about someone, either through a search engine such as Google or on Web logs, such as the one that Behl maintained at LiveJournal.com, where more than 8 million people, most of them teenagers and college students, document their thoughts.

"It's real surprising what people put out on the Internet about themselves, what they're interested in, what they're thinking," said Richmond police Detective Jeff Deem, one of several officers assigned to Behl's case. "Every case is different, but if we know that someone is a heavy Internet user, we're going to go online and look around."

Behl, a June graduate of James Madison High School, created her Web log, or blog, on April 6, 2004. With neither an introduction nor an acknowledgment that it was her first entry, which she titled "Oh la la," Behl wrote that her mother found out that a boy had visited while she was out. "I'm just trouble," she wrote. Two weeks later, on April 20, she "decided that all boys suck."

Mostly, Behl's online writings captured the angst and mood swings typical among teenagers.

There were moments of sadness: "I now know that everyone is useless and really doesn't care."

There were moments of anger: "I'm so [expletive] tired of everyone making decisions in my best interest. Don't I get a [expletive] say? NO. Sorry, not 'til you're 18."

And there were moments of utter and exposed joy: "I'll have my own car on Sunday . . . yesssssssssssssss!"

Behl's entries serve as a permanent link to the VCU freshman, whose whereabouts remain unknown. In the weeks since Sept. 5, when she was last seen, visitors to her blog and MySpace.com profile have posted numerous messages, imploring the teenager to come home. Others are not so optimistic that she has the option.

Police now suspect that Behl might have been abducted. Her 1997 white Ford Escort was found with stolen Ohio license plates on it about a mile from campus several days after she left her dorm after finding her roommate with a boyfriend. She left with only her car keys, cell phone, student identification card and about $40.

In the hours after her roommate reported her missing, police were aware of Behl's vast online presence. They tapped into her accounts and into the hard drives of her computers, allowing for cyber canvassing, the online equivalent of soliciting for clues in the areas she was known to frequent.

"This information is in many ways as good as fingerprints," said Ernie Allen, president and chief executive of the Alexandria-based National Center for Missing and Exploited Children, which serves as a liaison between law enforcement and families of missing kids. "It enables you, because kids are online so much, to really develop a pretty thorough profile of where that child has been and with whom they've communicated."

Behl was popular online, with 92 people listed as her friends at MySpace.com, a social and networking Web site with more than 31 million users, many as young as 14. Among them was Ben Fawley, a 38-year-old photographer with whom she had a romantic relationship. Fawley, one of the last people to see Behl, was arrested last week on charges of possession of child pornography, and his apartment has been searched for Behl's belongings. He used the screen names "Skulz" and "Skulz67" and left messages for the teenager at her various sites.

Fawley -- a father of two who maintains numerous Web sites dedicated to his interests in art, Goth culture, skulls and a bumper sticker-plastered van that he decorated with dozens of license plates he collected -- took pictures of Behl, fully clothed, and posted them online among collages of short-skirted girls he claimed to have also photographed. They were removed shortly after she vanished. No one has been charged in her disappearance.

Although Behl is missing and Fawley is jailed in an isolation cell in Richmond, the threads of their relationship remain online. In a blog entry dated 6:57 a.m. April 8, not long after she met Fawley for the first time at his apartment near the edge of the downtown VCU campus, Behl asked that people post memories they had of her, anything "good or bad. Just so long as it happened."

Skulz67 was the first to respond: "This very attractive girl climbed up into my bunk @ 407 [the address of his apartment], the last girl to do so before the move. . . . "

Behl wrote back: "well I was curious."

Skulz67: ". . . so was I . . . fact I still am . . ."

While those investigating Behl's disappearance would not comment specifically about her case because it is a criminal probe, they said during the initial stages -- when she was merely a missing person -- that they had pored over her journal entries and profiles, including all of the messages left by Fawley and her other friends. Their search led them to the online ledgers that Fawley and the others maintained, they said.

"As police officers, we're always looking for additional ways to pull in information for our investigations," said Deem, who is assigned to the homeland security and criminal intelligence unit of the Richmond police. "The Internet has been our big source. Sometimes we're able to glean things from it that we don't find elsewhere. People sometimes don't think about what they're saying; they don't realize so many people are watching."

In the same way that investigators rely on cyberspace for traces of crime victims, they also troll it for suspects. But just like tips gathered in more traditional ways -- interviewing friends, checking bank accounts and visiting locations the missing person frequented -- many clues found online lead nowhere.

"Lots of stuff that is posted are just ramblings and end up meaning nothing," said Lt. Michael Pavlick, commander of the intelligence unit for the D.C. police. "But these are real diaries. The kids don't hide them under their mattresses anymore; they put them online for everyone to see, and you can really learn so much."

Behl's mother said that she knew of her only child's Internet habits and that Behl loved being on the computer. But in the weeks since her daughter has been missing, Janet Pelasara has read and reread the online journal and grown closer to her daughter in her absence.

"I've learned a lot about her, things I wish I had known earlier," she said in a telephone interview from her Richmond hotel, where she has been staying since Behl was reported missing. "I think it's great that the police are able to use what they find on the Internet. If only she had written more information about where her head was at or who she was hanging out with, then maybe she would have already been found."

Taylor Behl, a graduate of James Madison High School, created her LiveJournal.com blog on April 6, 2004. Police have since used it to learn about her life and friends.