the best thing is to have only good people. if he was good he wouldnt have considered it.
theres many ways to create a good person just like creating a bad one.
the enviroment, the things you eat, the people you see, the things you read, the activities you choose etc theres a huge list. the parents and schools have a big role too
think of a pitbull dog. its not a bad dog until something happens to it creating a bad dog.
everything is born good but the things it encounters can change it to a bad one. if we can avoid all the bad things that create bad people we would have a better place to live. thats the simplest way to approach this.
taking guns away from good people will not stop a bad person. writing a new law will not stop a bad person