Had this guy ever exhibited any cruel or violent behavior in childhood? Had he ever been considered strange by his peer group? His father was a criminal; what was his mother like? The rage was probably simmering; he might have been a volcano waiting to erupt for the longest time.
Considering his gambling passion, I wondered how much an addiction to risk or cheap thrills played into this, along with a need for power. The victims were all in an enclosed area, making them sitting ducks. He could feel omnipotent.
Just my .02.
His brother seemed ... odd. The wide eyes. The ‘hit by an asteroid.’
He also lacked any emotional response for either his brother or those that were harmed or the families of the dead.
Then to say his brother has no politics at all? Odd.