Philip Agre was an associate professor of information sciences at the University of California at Los Angeles, and for years he ran a popular technology e-mail list with thousands of subscribers. But one day the 49-year-old scholar just stopped showing up on the campus, and now colleagues have deployed Twitter, Facebook, and the Web to try to find him.
Last month the university police department put out a missing-person alert for Mr. Agre, whose absence was reported to authorities by his sister. The alert says he abandoned his apartment and his job "sometime between December 2008 and May 2009." It also notes that he suffers from "manic depression."
The scholar apparently had many professional contacts but few close friends. An expert on privacy, he was always guarded about his own, say those who know him.
"In his personal life, he never wanted to discuss social things," said Charlotte Lee, an assistant professor of human-centered design and engineering at the University of Washington who worked under Mr. Agre when she was a doctoral student. "When his behavior got more erratic, nobody felt close enough to him to help, and we thought we'd help by protecting his zone of privacy," she said. "Respecting that zone of privacy is what allowed him to slip away."
Ms. Lee helped set up a Web site last month asking the scholar to get in touch with his friends. The goal is to make sure he knows he is missed, she said. "Phil, if you are reading this, please let us know your whereabouts, how you are doing, or if there is anything you need," reads a note on the site. "We care."
Several scholars who have worked with Mr. Agre over the years have posted notes to the site wishing him well, with a tone that is a mix of extending a hand and offering tribute.
"You taught me how to be a graduate student and burgeoning scholar. Thank you," wrote one former student. "I wish you only the best and hope that you are well."
Pat Hayes, a senior research scientist at the Institute for Human and Machine Cognition, wrote on the site that he has a book that Mr. Agre lent him. "Who knows, maybe Phil will come out of hiding for the sake of getting his book back," Mr. Hayes said in an interview Wednesday. He last saw Mr. Agre at a conference 10 years ago, where they argued professionally about a technical issue. "He's one of the smartest young people I've ever had the pleasure of disagreeing with," Mr. Hayes said.
Some of the people leading the online search have never even met Mr. Agre, but felt they knew him through his former e-mail list, the Red Rock Eater News Service. The scholar stopped operating the list in 2005, but it was an influential information source throughout the 1990s.
Among the strangers who have mobilized are Seb Paquet, a professor of computer science at the University of Quebec at Montreal, who started a Facebook group to help find Mr. Agre after he read online that the scholar was missing. "I really hope if he's around that we can bring him back because he was doing really valuable contributions to issues around the social impact of the Internet," More than 80 people have joined the group since it was set up last month.
Mr. Paquet and others have used Twitter to spread the word about the Facebook group and the Web site, trying to cast a wide net online in hopes that someone is in touch with Mr. Agre or knows where he is.
UCLA officials said that Mr. Agre no longer works for the university, but they refused to provide details, citing privacy laws.