It's David Katz in his own words.
Katz, then 16 years old, sent a handwritten letter
to the judge presiding over his parents bitter
divorce case.
"I hate her more than anything in the world,"
he wrote about his mother.
"I hate everything about her."
Katz had severe mental issues and was treated
at two medical hospitals as a teenager.
He also spent more than three months at this
wilderness survival camp in Utah for troubled teens.
According to his parents divorce papers,
Katz was treated for schizophrenia with antipsychotic
and antidepressant drugs.
"David would go days without bathing,
"would play video games until four AM on school nights,
"would walk around the house in circles,"
said the judge.
Once, when his mother hid his game controller,
he punched a hold in her bedroom door.
Sometimes, he'd curl up in a ball and sob.
Forensic psychologist, Dr. Judy Ho.
David was playing games for the majority of time
that he was awake on some days.
I mean, really he was playing games exclusive
to the fact that he wasn't even taking care of
the rest of his life anymore.
He was failing in school.
He wasn't doing his homework.
He wasn't engaging in the real world with anybody
and this was really his entire identity.
Kevin O'Sigh, who attended high school
and the University of Maryland with Katz,
says Katz had an explosive temper.
If he got upset, he would get vehement,
very upset, ya know, all at once.
He was seeing the school counselor fairly often
throughout pretty much like all of high school.
The shooting spree in Jacksonville
is shedding light on the world of pro gaming,
now a one billion dollar industry.
This is the spectacular opening ceremony
of a tournament for a game called League of Legends.
360 million people worldwide watched the event
streamed live online last year.
Three times as many has watched the Superbowl.
(dramatic music)
