Her 29 clips - with titles like I Probably Shouldn't Post This..., Boy Problems... and My Parents Suck... - have been viewed over 2.3 million times. And with 23,369 subscribers, Lonelygirl15's channel has become the second most popular YouTube video feed of all time.

But viewers started to smell a rat. Was the wide-eyed, 16-year-old beauty who claimed to have spent time with her parents in a commune in New Zealand the real thing? Or was this a clever viral marketing campaign, a masterful hoax that had fooled most of the people, most of the time? "She's just a little too charming, her videos a little too well edited, and her story a little too neatly laid out," Adam Sternbergh wrote in the New York magazine late last month.

It emerged that the lonelygirl15.com website had been registered a month before her first video post and, later, that an application to trademark Lonelygirl15 had been lodged by a Los Angeles lawyer. Finally on Friday a breakthrough. The Los Angeles Times reported that online sleuths using email tracking software had pinpointed the source of emails sent by lonelygirl15 to a Hollywood talent agency called Creative Artists Agency.

A spokesman for the agency told the paper that he could "neither confirm nor deny" links with lonelygirl15. Soon after the report was published on the internet a notice purporting to be from a group of independent filmmakers appeared on one of the Lonelygirl15 discussion sites. "To Our Incredible Fans", it began. " Thank you so much for enjoying our show so far. We are amazed by the overwhelmingly positive response to our videos; it has exceeded our wildest expectations. With your help we believe we are witnessing the birth of a new art form."

The message went on to explain that Lonelygirl15 was a project to harness the audience to develop and evolved a story and "usher in an era of interactive storytelling where the line between'fan' and'star' has been removed". While not everyone is convinced that the filmmakers' confession is genuine (many believe it's part of the developing mystery), it now seems certain now that Lonelygirl15 is a fake - although who is behind the hoax and what is purpose of the elaborate ruse is still unclear.

A clue left in one of the videos suggests it may be another month before we find out. In a video posted a week ago titled Bree The Cookie Monster, Bree and Daniel rate batches of cookies they said they baked. Bree's purple monkey puppet holds up score cards. The first one gets "10", the second "12" and the third one "06". Why "06" and not "6"?

Viewers point out that the sequence makes a date 10/12/06 - or October 12, 2006, using the US method of writing dates. October 12 also happens to be the birth date of the late occultist Aleister Crowley, whose picture can be seen on a wall in Bree's room. News of the hoax, however, does appear to have dented Lonelygirl15's popularity.

"Hi. You are a great actress," Daniel Gardner said in a message left on Lonelygirl15's YouTube site on Saturday. "We hate your director and crew ... but can't help loving you."

MashUp Blog: Lonelygirl theories, please

