Two weeks before William Freund donned a mask and cape and fatally shot two neighbors before killing himself, members of an online forum for people with a rare mental disorder read the 19-year-old's string of violent rantings.
Freund's online musings and his pre-Halloween rampage raised fresh questions about the little-policed world of Internet discussion rooms: What, if anything, should Web site gatekeepers do when users post threatening messages online?
Internet law experts generally agree there is no legal onus on site owners or users to notify police. Cyberspace is so intricate and its users often anonymous that to react to every threatening post would be impossibly time-consuming and expensive.
Still, ethicists say operators should try to alert authorities if they believe a user is serious about committing harm. While monitors of Freund's postings unsuccessfully tried to reach his parents, they didn't reach out to authorities.
"If there are signs that people are going off the deep end and we don't do anything about it, then it could have calamitous results," said Richard Spinello, a Boston College professor who specializes in technology and ethics.
In recent years, a handful of chat room users who published violent messages have been prosecuted, but such threats rarely are carried out, legal experts say.
Web sites where the threats are posted are rarely sued because they're not legally bound to alert police, said Nicolas Terry, an Internet law expert at Saint Louis University's Center for Health Law Studies.
Before last Saturday's shootings, Freund begged for help and told an online message board for people with Asperger's syndrome, a neurological disorder marked by a lack of social and communications skills, that he was lonely and suicidal and would begin a "terror campaign to hurt those that have hurt me."
Some users of the Web site, wrongplanet.net, thought Freund was crying wolf. Others reached out with advice.
"He seemed really troubled, but he didn't seem like the type of person who would do this," said site operator Alexander Plank, 19, a computer science student at George Mason University.
Since the killings, Plank said, the site's monitors have become more vigilant about online postings and are debating whether to collect information about users. One Internet scholar warned against that approach.
"It is very risky to impose responsibility on Web site owners to police their users," said Jennifer Granick, executive director of Stanford University's Center for Internet and Society. "How do you know if someone is serious? Are you making a big deal out of nothing? How hard are you supposed to try? Are you betraying the person?"
In recent years, online chat rooms have mushroomed into virtual communities where people can reinvent themselves behind screen names. For people with a rare disorder such as Asperger's, interacting online can be especially therapeutic.
But online forums can also free some users to post exaggerations or lies, making it difficult for webmasters to distinguish fact from fiction. And many of those message boards are patrolled by volunteers who may not be able to recognize a problem because they are young or not trained as mental health professionals.
After the shootings, one member of wrongplanet wrote that, "no-one here has the capability - in any practical sense - to offer the level and sort of help needed."
Complicating the matter are privacy laws and Web site policies that prohibit operators from surrendering personal user information to the government, unless there is an immediate danger.
Authorities are still trying to determine what set off Freund two days before Halloween, when he drove to his neighbors' home in Aliso Viejo, a wealthy section of Orange County and killed a father and his 22-year-old daughter. The teen also fired into another home, wounding the person inside, and tried to shoot another neighbor. When his gun misfired, he went home and committed suicide.
Orange County sheriff's spokesman Jim Amormino later urged Internet users to call police if they notice suspicious postings.
After the shootings, the wrongplanet site fluttered with comments.
"I think if there is ever another member here who says things about wanting to harm people," read one posting, "we should do something about it. I don't know what we can do, though."