Penn. Gov. Ed Rendell commented on the blog during a news conference saying "someone with those psychological barriers or challenges in my judgement shouldn't be in possession of multiple semi-automatic weapons."
"If you look at the blogs; this gentleman had severe mental problems. He had a deep and abiding hatred for women," Rendell said.
Sodini was the registered owner to at least three of the four guns he used in the attack.
Malley said she didn't see Sodini enter the room but said she felt a presence of "someone who didn't belong there." Then the room went dark.
"Everyone was just screaming so loud. At first I didn't even think shots were being fired," she said. "It was so surreal."
Then, as she realized what was happening, Malley and her friends found their way out of the room, guided by the lights in other parts of the gym.
"I just ran as fast as I could," she said, adding that she went back to make sure her best friend was behind her. "It was just a blur from there."
On Monday, the day before the shootings, Sodini gave what might be the closest thing to his reason for the attacks.
"The biggest problem of all is not having relationships or friends, but not being able to achieve and acquire what I desire in those or many other areas," the blog reads. "Everything stays the same regardless of the effert (sic) I put in. If I had control over my life then I would be happier. But for about the past 30 years, I have not."
Sodini had apparently been planning the attack for some time, even writing that he put off his original plan until after November's 2008 presidential election, in a rambling entry that complains black men have their choice of the best white girls.
He tried again in January and May, according to the blog, but "chickened out."
The Jan. 6 entry said he even brought the loaded gun to the gym.
Roberta Kozel, who co-owns a tanning salon that Sodini frequented as recently as Saturday, said she was shocked to learn he was the shooter.
"He didn't seem like a violent person," Kozel told ABCNews.com. "He seemed like a typical class nerd. He was a little odd but you could never figure out what it was."
Sodini asked the receptionist at the salon out for a date, but she "didn't take him seriously," Kozel said.
A lengthy New Years Eve entry in the online diary lists his family members by name and, in some cases, address. He described his older brother Michael Sodini as a bully -- the "kind of guy you actually loved to hate."
He described his mother as the "Central Boss" warning, "Don't piss her off or she will be mad and vindictive for years. "
Various blog entries detail his worry about losing his job and having to re-enter the job market, as well as his troubles with alcohol.
A May 5 entry -- the day of his second attempt to launch an attack on the gym -- notes that he stopped to buy a bottle of Jack Daniels, his first drink in 20 years.
A woman in the class of about 30, who identified herself as Nicole, told WTAE that the class had started about 10 minutes before gunfire erupted.
"He looked out of place in a class full of women," according to the witness, who said the man put his bag down, turned the lights off and opened fire.
Ron Fleeher told WTAE Channel 4 Action News that the gunman held down his niece before shooting her.