John Gibson's Facebook page was a window into a dangerous social life, one his parents and professors knew little about.
Wall posts about drugs and "crazy co-op parties" -- a reference to student life at the University of California at Berkeley's Cloyne Court Hotel -- and photos of Gibson downing tequila hinted at habits that would dim the college junior's bright future.
"Once you start putting that on Facebook, it's not a one-time thing," said Gibson's mother, Madelyn Bennett. "Had I gone on his Facebook page earlier, I probably would have called him home from school for drug and alcohol counseling."
By the time Bennett saw her son's Facebook profile, it was too late. Gibson had overdosed. Toxicology tests would find cocaine, alcohol and marijuana in his blood, and he would awake from a coma six weeks later with irreparable brain damage.
Up to 98 percent of U.S. college students use social networks such as Facebook -- a fact some health experts hope to use.
"I think Facebook is a new window on an old problem," said Dr. Megan Moreno, a pediatrician at UW Health in Madison, Wis. Moreno has been studying whether online posts can predict offline problems, from drug and alcohol abuse to depression. "I don't think we can use Facebook to make a judgment, but we can use it as a trigger to ask more questions face-to-face."
Before the overdose, Gibson was a Regents and Chancellors Scholar at Berkeley, majoring in peace and conflict studies with a minor in pre-med.
"He planned to work for Doctors Without Borders," said Bennett, who lives with her son in San Diego. "Now we're hoping he'll be able to go to bathroom on his own."
Gibson's round-the-clock nursing care costs more than $250,000 a year. On Feb. 23, Bennett filed a lawsuit, claiming Berkeley knew about drug abuse at Cloyne and failed to protect the students.
"They were more concerned about protecting the privacy and criminal behavior of students than safety," she said.
Calls to Cloyne were not immediately returned.
The thought of using Facebook to flag risky, potentially illegal behavior raises ethical and legal questions: What should people do if they suspect a friend is in danger? And if they do nothing or their actions cause more trouble, are they liable?
Moreno said society is "still learning" what to do with the scores of information made public on Facebook. "And yes, we should be thinking about the ethical and legal side of this," she said. "But we can't let that get in the way of us just asking, 'Are you OK?'"
For someone like Gibson, who has more than 800 Facebook friends, people might be less likely to speak up because of a phenomenon psychologists call the "bystander effect."
"You can get a situation where 800 friends look around and say, 'I'm sure his three closest friends are looking into this,'" said Moreno. "It actually mirrors what happens in the offline world."
Aida Ingram, a youth counselor in Clayton, N.J., said it's better to speak up than to assume the person is fine.
"It's a shame for a whole community to watch a child spiral out of control, whether on Facebook or in the real world," said Ingram, whose daughter will soon head to college. "The last thing you want is to go to someone's funeral knowing you saw a worrying Facebook post and did nothing. I'd rather embarrass myself."
Facebook, too, is figuring out its role in keeping users out of harm's way. In December, the site launched a program that allows users to instantly connect with a crisis counselor through the "chat" messaging system. And on Feb. 2, two Colorado teens were credited with saving a suicidal teen's life through Facebook.
"He was posting goodbyes and 'I'm sorry' on his friends' walls," 19-year-old Gary Ramirez, one of the teens, told ABCNews.com. "If I didn't know this kid was safe, I wouldn't have been able to sleep. ... We tried to keep him calm until the police could find him."
Bennett said she wishes someone had reached out to her son.
"If your friends are experimenting with drugs or alcohol and have overdone it, it is your responsibility as a fellow human being to make sure they're OK," she said.
Bennett "usurped" her son's Facebook page after the overdose, which she uses to post uplifting updates to his many friends.
"John is making a new sound today," she wrote Feb. 13. "He is growling like a wounded bear. My new motto is that anything new is good."