I don't know how to call it, I just can say that not only did he kill absolutely innocent people, he left horrible inheritance to his son.
One question, though: they mentioned that allegedly he started hearing voices after his hearing aids were fitted? Can't comment on this, but given that several victims were deaf, did he know any of them, or maybe included deafness into his delusions? Besides being a mass murderer, he was a murderer who targeted people with a disability, which makes it as ugly as can be.