Lederer does indeed establish a connection between pornography and the rape and murder of women and children.
However, her evidence establishes the cause of such crimes as the abusive treatment of the perpetrators as children by their parents. "Most of their family histories revealed a severe pattern of physical, psychological and sexual abuse by their parents . . . " This, of course, is no surprise. We have long known that the cause of criminals is the criminal treatment they are subjected to as children. We just act as if we didn't know it.
The use of pornography is a symptom of derangement and we'll get rid of it (and other symptoms) when we get rid of our lackadaisical societal attitudes about parenthood--specifically the idea that it's everybody's right to have children.
We must all recognize that many of the people who have children aren't capable of parenting. We must educate our young to know the serious demands of that role and offer them guidelines to help them determine if they're up to it.
At the very least we must let those who recognize their unreadiness for parenthood have the option of legal abortion. The ominous trend toward outlawing abortion bodes worse for our society than pornography.