For nine months, George Sodini recorded into his computer a plan -- wrapped in anger, hurt and confusion -- that culminated in a shooting Tuesday evening at the LA Fitness center in Collier, leaving four dead and nine wounded.

Armed, he entered the gym where he often exercised. He turned out the lights, and as he released bullets blindly into an exercise room filled with women, he seemed to hope to release the emotions so fervently detailed in his electronic journal.

Isolation is the root of the problem, said Carolyn Wolf, senior partner at Abrams Fensterman, a New York law firm that specializes in mental health issues.

In a society where online social networks often replace interpersonal social networks, people become detached.

"The Internet allows for isolation. As a result we have less interpersonal communication and fewer opportunities to identify this behavior and intervene before something as tragic as this happens," Ms. Wolf said.

As people separate themselves from each other, they become less keen to simple human mannerisms -- facial expressions, voice tones, behavioral cues -- that indicate when someone is having a problem. And because dealing with a problem face to face is becoming ever rarer, many do not trust themselves to confront someone who seems distressed, even if they recognize warning signs.

"People probably noticed weird behavior but didn't really know what to do with it," Ms. Wolf said. "People don't trust their gut instincts as much as they used to because they're not interacting as much as they used to. So they second-guess themselves or they decide not to deal with it."

In entries from Nov. 5, 2008, to Aug. 3, 2009, Mr. Sodini chronicles his thoughts as he attempted to gain the courage to enter the gym with a gun.

Among other things, he also vented about his inability to cultivate friendships or relationships, discussed his resentment toward young women and allegedly abusive family members and mentioned that he learned in a church that God forgives mass murderers.

Paul Friday, chief of clinical psychology at UPMC Shadyside, said that, based on the blog, Mr. Sodini fits the mold of someone with antisocial personality disorder.

Criteria for the disorder -- such as failure to conform to social norms, impulsivity, irritability or aggressiveness, reckless disregard for the safety of others, and lack of remorse -- are all evident in his words, Dr. Friday said.

"It is a very difficult thing to treat, and my sense is that there was not treatment, which meant that this thing just festered," he said. "And when these things fester, the dam eventually breaks, and in this case, that meant a shooting such as the one last night."

In his blog, Mr. Sodini, 48, seems confused about why women will not get in relationships with him.

"No girlfriend since 1984. ... Who knows why. I am not ugly or too weird," he wrote in December 2008. And on another day:

"I dress good, am clean-shaven, bathe, touch of cologne -- yet 30 million women rejected me over an 18- or 25-year period. That is how I see it. Thirty million is my rough guesstimate of how many desirable single women there are."

Ms. Wolf said Mr. Sodini's self-confidence issues may have led him subconsciously to isolate himself from others, but to ultimately blame them.

"Sometimes it becomes a self-fulfilling prophecy," she said. "He knew he had trouble getting in a relationship, and he may have sent out those kinds of vibes. So women may have responded to that by not wanting to be in a relationship"

She said the blog could have been a way to identify in a community where he seemingly had no identity.

"In his mind, that was a way of venting, a way of putting it in people's faces, 'This is what society did to me, this is what my family did to me.' " she said.

Although Mr. Sodini obviously had mental health issues, he was not psychotic, Dr. Friday said.

Mr. Sodini may have had social problems, but he writes in the blog that he had a successful job, survived a layoff and received a raise.

"He was obviously bright, which points out that intelligence has nothing to do with emotional stability," Dr. Friday said. "He was not a healthy man. He was functioning, but he certainly wasn't healthy.

First Published: August 6, 2009, 4:00 a.m.