No one has publicly come forward to lay claim to her work, but she is starting to look as connected in Hollywood as any starlet. Three lonelygirl15-obsessed amateur Web sleuths set up a sting using tracking software that appears to show that e-mails sent from a lonelygirl15 account came from inside the offices of the Beverly Hills-based talent agency Creative Artists Agency.

The apparent CAA link takes its place alongside other tantalizing pieces of evidence that lonelygirl15 is not who she claims to be: a copyright for the name obtained by an Encino lawyer, and a plot line that, leading speculation suggests, will turn out to be the lead-in to a horror movie's marketing campaign. CAA spokesman Michael Mand said he "could neither confirm nor deny" that the agency is representing whoever is behind the 27 video posts. (Other talent agencies and production companies contacted by The Times denied any connection.)

As to horror film rumors, calls made to several studios found no such plans — but plenty of fascination for the way in which a Hollywood-ready cultural phenomenon has been built from a grass-roots Web platform. Lonelygirl15, many say, is the next-generation "Blair Witch Project," using interactive forms of storytelling that, like the 1999 hit, tries to trick an audience into thinking it's true.

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On June 16, lonelygirl15 made her first appearance in a video, titled "First Blog/Dorkiness Prevails." Dark-haired, big-eyed and pretty, she blinked nervously and hugged her knees as she described living in a small town "hours from a mall" with strict religious parents and a friend named Daniel, who she didn't like "in that way." Over the next three months, two dozen more videos hit the Web, spaced out every few days. Bree dangled hints about her life, revealing that she had spent her youth in New Zealand, was treated for "lazy eye" and had an obsession with physicist Richard Feynman. Oblique references popped up to "my religion," which was never named but which forbade things such as attending Daniel's high school graduation party. Fans soon started to notice jarring details. A music clip from an undiscovered L.A. band was mixed in to her well-edited montage sequences. Her room was movie-set neat. Above her bookshelf hung a photo of famed occultist Aleister Crowley. Thin already, Bree talked about an upcoming religious ceremony that she would participate in, even though it involved going on a diet.

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In late August, fans discovered that the Web address for lonelygirl15.com had been purchased before the first video even appeared, with efforts made to shield the identity of the buyer. In early September, Web forums erupted with the news that lonelygirl15 had been trademarked and the application filed by an Encino lawyer named Kenneth Goodfried. (He declined to comment for this article.) Within days, the MySpace profile of Goodfried's daughter was being combed for connections to the video.