Police confirmed that Mr Katz legally purchased two handguns in Baltimore a few weeks before the shooting, but that he had not fired both weapons during the shooting.
The competition was being live-screened, and viewers were able to see players reacting to gunshots and hear screams before the footage was cut off.
According to court records in Maryland accessed by AP, Mr Katz was hospitalised twice in psychiatric facilities as a teenager, and was prescribed antipsychotic medication. His parents divorced in 2011, with records detailing their disagreements of their son’s mental state and how it should be treated.
In 2017, Mr Katz won a similar live-screened tournament. Video footage shows commentators discussing the gamer, saying that he “keeps to himself. He’s a man of business… he’s not here to make friends.”
Maryland law requires gun buyers to disclose previous history of mental illness when attempting to purchase firearms.
It was unclear whether Mr Katz revealed this information when purchasing the weapons.
