Samuel Wurzelbacher, better known as Joe the Plumber, insisted the deaths of innocent people "don't trump" his constitutional rights in an open letter to the families of victims in Friday's shooting rampage near the University of California, Santa Barbara.

Wurzelbacher said the words of Richard Martinez, whose son Christopher Martinez was a victim in Friday's incident, "will be exploited by gun-grab extremists as are all tragedies involving gun violence and the mentally ill by the anti-Second Amendment Left." The former Congressional candidate told Martinez to "back off."

Wurzelbacher said his letter is directed "only to the families of the gunshot victims in Santa Barbara" and not to the families of three who were stabbed ahead of the shooting spree.

"I am sorry you lost your child. I myself have a son and daughter and the one thing I never want to go through, is what you are going through now. But: As harsh as this sounds -- your dead kids don’t trump my Constitutional rights," Wurzelbacher wrote.

Wurzelbacher acknowledged his comments are "harsh" but claimed pro-gun control activists "don't care about your family or your dead children at all."

"They sound like they do, whereas I sound uncaring and like I say, harsh," Wurzelbacher wrote. "Don’t be fooled – I care about your family and mine. The future of our very liberty lies in the balance of this fight."