NEWTON, Conn - More information is being released on the alleged Newtown school gunman, 20-year-old Adam Lanza.

It has been confirmed that Lanza was diagnosed with Aspergers Syndrome, which is a mild form of autism. His brother also claims that Lanza had a personality disorder.

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Janet Pfeiffer, a New Jersey-based authority on anger management and conflict resolution, says that most spree shooters share common traits. "Very often these young people have poor impulse control," Pfeifffer says. "So they feel this surge of emotion whether it's anger or fear or rejection and they act impulsively on it they don't know how to process these emotions. They don't know how to process them in a rational and cohesive way."

Some sources speak of Lanza as being painfully shy, isolated and obsessed with video games. His brother says that he had access to a number of high-powered firearms that were owned by their mother.