PORT RICHEY, Fla. - Brian Disario believed his mother's friend was hitting on his girlfriend.

Disario doesn't have a girlfriend.

The assumption resulted in the 30-year-old shooting his mother's friend, David James Armstrong, to death in front of her and her boyfriend, then engaging in a shootout with two Pasco County Sheriff's Office deputies in an area where parents usually wait to pick up their children from Gulf Highlands Elementary, officials said.

Disario has a history mental illness, a condition Pasco County Sheriff Chris Nocco said forces deputies into dangerous situations.

"The other part about law enforcement is we have to solve complex problems," he said during a press conference following the shooting. "We're called to solve every complex problem, but the reality is mental illness and addiction is a healthcare issue. We unfortunately get caught up in the mix because they think law enforcement can solve everything out there, but until addiction and mental illness is defined and everybody looks at it from a healthcare issue, we're going to keep seeing these situations over and over again."

Disario, after killing Armstrong, exchanged bullets with two deputies that Nocco said were close enough "to actually see his facial reaction."

"This individual, no fear, he was shooting at law enforcement and knew he was shooting at law enforcement," Nocco said.

Disario was later found dead inside a home. Authorities did not immediately say if he died as a result of the gun battle.

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