Emotionally abused and rejected (and sentenced to a state hospital as a criminally insane juvenile), extremely tall and smart Edmund Emil Kemper III, a.k.a. the Co-ed Butcher, killed his paternal grandparents, six hitchhiking female college students, his mom and his mother's best friend from 1964 to 1973 before telephoning police to confess. This outwardly "gentle giant" shattered the peace in the Santa Cruz, California, area and stunned police by his friendliness to them, his method of decapitating, dismembering and perversely violating his victims, and being the only murderer to their knowledge of leaving a note of apology at a crime scene.
—statmanjeff