An Expert Weighs in on What Caused the Vegas Shooter to Kill

Two weeks after the massacre in Las Vegas, authorities are still unsure about what drove the domestic terrorist behind the attack to kill.

In a new interview with People, criminal profiler John Kelly theorizes that there was a perfect cocktail of stressors in gunman Stephen Paddock's life that slowly could have built him up into a madman.

"What would drive somebody that is so methodical and structured in life to go insane in a very structured and methodical way?" Kelly said. "Paddock was a pathological gambler, psychopath and a sociopath. He was predisposed from birth and childhood to harbor extreme internalized shame, low self-esteem, depression, and aggressive anger."

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Since the any physical abnormalities were ruled out in the autopsy, Kelly hones in on Paddock's childhood and genetic makeup. He thinks the shooter's father, bank robber Benjamin Paddock, could have passed on a gene that gave Paddock the potential to become a psychopath.

"After eliminating any physical precursors to Mr. Paddock's murderous rage, we would need to start to look at this individual's beginning, which was in the womb," Kelly said. "The strongest genetic connection of the psychopathic gene, the 'Warrior gene,' is transmitted from father to son. This gene can cause extreme violence in an individual."

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Kelly also touches on the fact that Paddock's medications could have cause him to become exasperated, and his upbringing and possible mental health issues may have "produced internalized rage within him."

"This was exacerbated with pathological gambling, Valium and alcohol that caused the perfect storm for mass murder: a delusional, psychotic illness which resulted in violent, suicidal, and explosive murderous rage," Kelly said.