Doctor Jeremy Richman lost his daughter five years ago in the Sandy Hook school massacre and he's urging more attention to the mental disorders behind such attacks.

One man who knows the horror of a mass shooting all too well is bringing his search for answers to Rochester.

Doctor Jeremy Richman lost his daughter five years ago in the Sandy Hook school massacre and he's urging more attention to the mental disorders behind such attacks.

Richman teaches people to try to understand violent incidents like the Las Vegas attack. He knows their impact all too well. His six-year-old daughter Avielle was killed in the 2012 Sandy Hook shooting rampage.

"I get, honestly, a little bit angry," says Richman. "Because, you know, everybody keeps saying 'what's going to be the tipping point?' 'What's going to be the change?' You know, if 20 six and seven year olds doesn't do it, what is going to do get people to get involved."

Richman says the country does need to consider who can handle the responsibility of having a gun. But he also founded his Avielle Foundation -- named after his daughter -- to encourage a better understanding how mental disorders turn people into mass murders like the Sandy Hook shooter Adam Lanza. Richman says he's waiting to see what signs the Las Vegas shooter Stephen Paddock showed.

"The Sandy Hook shooter had problems his whole life that many people in the community and his family were very aware of," RIchman says, "but they didn't do anything about it."

Richman says people with heart problems, obesity or liver disorders are routinely diagnosed and treated but that he has to fight against reluctance and stigma when it comes to confronting sickness in a crucial organ like the brain.

Richman says, "Does this fear of a stigma gets people killed? In my opinion, yeah, that was one of the leading causes of the murder of our daughter. Why wasn't there significant help pursued? Because of that fear of stigma."

He adds, "It takes a lot of courage to recognize you need to do something to take action."