As the chaos clears and YouTube looks for a new normal, police and pundits look for answers, especially to the question "Why?"
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A quick scroll through the shooter's now-deleted YouTube posts reveals goofy glamour shots and commentary on veganism, animal cruelty, and exercise. Plus, some pot shots at the platform itself.
"There was something going on with her psychologically that made her different from most people we would normally see," said Dr. Eric Hickey. "She struck me as extremist in her thinking and almost maybe a little bit paranoid."
Dr. Hickey is a forensic psychologist specializing in criminal profiling and a former consultant on the FBI's UNABOM task force.
He says the shooter may have had mental health issues making it tough for her to get a job, and she clearly felt singled out by YouTube for demonetizing her videos and cutting her ad revenue.
Neighbors say she kept to herself, so he suspects she was a loner who lost contact with reality.
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YouTube says she drove into a parking garage and walked to a courtyard, but never went into the building, but Dr. Hickey thinks since she didn't fit the typical mass shooter profile, getting past security wouldn't have been hard.
"I suspect because she didn't look like a problem - again, being female and we don't usually see females act out this way - that she could've just easily walked in and blended in with everybody else," he said.
Less than three percent of mass shooters are women.
"Women are not as socialized to guns as men are," Dr. Hickey said. "They have other ways to act out."
But he says extensive coverage of mass shootings could be a tipping point, leading to more violent acts by women.