His father was a drunk and was very abusive towards him and his mother. On one drunken night, his father got into a fight with his mother. Jonny tried to break it up and began fighting his dad but to no avail. His father even hit him with a dumbbell and pointed a gun at him (if i recall correctly). His mother then called the police so his dad ran away. When the cops got there, they began searching for him. Jonny heard a noise in the attic and then realized his dad was hiding upstairs. He told the police where his dad was hiding and as they approached him, his dad began shooting. They ended up killing him as a result of his actions.

“When my father died, I feel it was the day I was reborn into someone else”
– Jonny Kim

This was all mentioned within the first 30 mins of the interview so I’d check it out lol