There is no such thing as "gun violence", as that puts the responsibility for the violence on the gun, rather than on the sociopath wielding it. With two decades of known criminal activity under his belt, the perpetrator of this crime should probably have been removed from society long ago. What we need are laws that allow for the scaling of penalties based on all criminal behavior, not just the most recent case, but juries are often not permitted to hear about a defendant's previous encounters with the law. They are often permitted to hear about previous activities of the witnesses to the crimes so as to credit or discredit their testimonies. This is not fair to the People nor to the justice system. To make matters worse, the prosecutors are often allowed to determine which cases to bring to the courts, regardless of what the laws themselves say.