It is not about guns.  Guns were the method used to murder the innocent.

Rosario Espinoza, 33, was once a neighbor of Mr. Mercer’s and moved into the apartment that the mother and son shared when the two moved from Torrance a couple of years ago. She said that the two had “kept to themselves,” but that from time to time Mr. Mercer’s mother would complain that Ms. Espinoza’s young children were playing too loudly and bothering her son.

“They’re normal children that play, but she would get really upset,” Ms. Espinoza said. “It was during the daytime. But I guess the noise would really upset him, the son.”

Other neighbors said she would confront them about their barking dogs when they returned from work. “She would wait till they got home and knock on their door,” Kim Hermenegildo, 48, said.

In the offline world, Mr. Mercer’s mother sought to protect him from all manner of neighborhood annoyances, former neighbors in Torrance said, from loud children and barking dogs to household pests. Once, neighbors said, she went door-to-door with a petition to get the landlord to exterminate cockroaches in her apartment, saying they bothered her son.

“She said, ‘My son is dealing with some mental issues, and the roaches are really irritating him,’ ” Julia Winstead, 55, said.

This is but only one of what I am sure were many things this young person had problems with. He was 26 years old, never had a girlfriend.  Obviously there is a problem when he mentions that he didn’t have a relationship with anyone, including and animal.

Well, it means I’ve never been with anyone, no woman nor man(nor dog or animal or any other)

His response is telling:

Involuntarily so

His online dating profile.

It said he enjoyed horror movies and under hobbies, it listed “killing zombies” along with the “Internet” and other pursuits.

Yes he was an adult, but this did not come to be overnight.  He had been diagnosed as having Aspergers.   IMHO, sounds like there was lots of catering to this nutjob.

I have an entire family of crazy living across the street from me.  First there is the young, physically healthy individual in his mid 20s that runs around in his jammies all day long fixing the home security cameras (so they look into the neighbor’s bedroom window) and playing on the internet. Every once in a blue moon he does go outside to pick weeds from the dirt lot they use as a yard at 9:30PM.  Any animal that dare cross into their dirt lot is poisoned.  Daddy died in a road rage incident.  The son not being any different (assaulted a postman).  Then there is the young one that mama uses to ensure the entitlements keep coming.   The kid is mentally challenged child? and is only allowed outside at night when no one can see him although we can all hear him.  During the day, he’s always in a carrier but at night under the cover of darkness he is behaving like Ruprecht.  The older one picks weeds from the dirt lot that they have sterilized (Monsanto would be proud)  called a yard at 930pm (long after the sun has set).  Why?  Who knows?  And yes, I do believe that this dysfunctional family could very easily harm anyone.  They are crazy and I will never be surprised at anything that they do.