Matt Foremski, the 18-year-old son of Tom Foremski, a reporter for the blog Silicon Valley Watcher, was the first to disinter a trove of photographs of the familiar-looking actress, who portrayed the character named Bree in the videos. The episodes suggested Bree was the home-schooled daughter of strictly religious parents who improbably stole time to upload video blogs of her innermost thoughts.

The discovery and the swift and subsequent revelation of other details surrounding the perpetrators of the videos — and the phony fan site that accompanied them — marks the end of one of the Internet’s more elaborately constructed mysteries. Whether fans, whose disbelief in lonelygirl15 was not willingly suspended, but rather teased and toyed with, will embrace the project as a new narrative form, condemn it, or simply walk away, never to be fooled again, remains to be seen.

The masterminds of the “lonelygirl15″ videos are Ramesh Flinders, a screenwriter and filmmaker from Marin County, Calif., and Miles Beckett, a doctor-turned-filmmaker. Many of the lonelygirl15 videos were shot in Mr. Flinders’s bedroom. Together with Grant Steinfeld, a software engineer in San Francisco, Mr. Flinders contrived to produce and distribute the videos so as to pique maximum curiosity about them.

The photographs of the actress, which made it clear that Ms. Rose has been playing Bree in the videos, were found through Google…

Last month, a lonelygirl15 fan discovered and posted a trademark application by Mr. Goodfried, which seemed to prove that the videos, which presented themselves as nothing but a video diary, were at least in part a commercial venture. Then, last week, three tech-savvy fans, working together, set up a sting on the e-mail address that was being used by “Bree”; the operation netted them the Internet address of a computer at Creative Artists Agency.

On the strength of this information, Mr. Foremski was confident he could find some trace of “Bree” on the Internet. He was sure that any participant in a semi-professional production like “lonelygirl15″ would have posted pictures somewhere. Sure enough, he was right.

Mr. Steinfeld, on learning that Mr. Flinders and Dr. Beckett had been found out, offered his photographs of Ms. Rose as proof of his involvement in the “lonelygirl15″ videos. He had been hired to take the on-set pictures at the start of shooting.