Uh, okay. A largish, disturbing passage including introspection from a mass murderer with a plausibly (edit: was "presumably") behavior-altering brain tumor follows. The amount of lucidity one can have about acting in a deranged manner is rather thought-provoking.
"After brutally murdering his mother, Charles cleaned up the mess, and placed her in bed with a notepad laying across and covering up the massive wound in her chest. Charles had left a note. It read: "To Whom It May Concern: I have just taken my mother's life. I am very upset over having done it. However, I feel that if there is a heaven she is definitely there now... I am truly sorry... Let there be no doubt in your mind that I loved this woman with all my heart."
After killing his mother, Charles returned home, planning on killing his wife "as painlessly as possible.," as he explained in yet another note:
"It was after much thought that I decided to kill my wife, Kathy, tonight....I love her dearly, and she has been a fine wife to me as any man could ever hope to have. I cannot rationally pinpoint any specific reason for doing this..."
Apparently she was sleeping, and after removing the blankets to expose her nude body, he viciously stabbed her repeatedly with his huge hunting knife, leaving five gaping holes in her chest. She died instantly.
Charles wrote another note which he left with the body: "I imagine it appears that I brutally killed both of my loved ones. I was only trying to do a quick thorough job... If my life insurance policy is valid please pay off my debts... donate the rest anonymously to a mental health foundation. Maybe research can prevent further tragedies of this type."
And then he added a post script beneath his signature: "Give our dog to my in-laws. Tell them Kathy loved "Schoci" very much."
The next morning Charles Whitman climbed the University tower carrying several guns, a sawed off shotgun, and a high powered hunting rifle, and for the next 90 minutes he shot at everything that moved, killing 14, wounding 38.
Post-mortem autopsy of his brain revealed a glioblastoma multiforme tumor the size of a walnut, erupting from beneath the thalamus, impacting the hypothalamus, extending into the temporal lobe and compressing the amygdaloid nucleus (Charles J. Whitman Catastrophe, Medical Aspects. Report to Governor, 9/8/66)."
(see also https://en.wikipedia.org/wiki/Charles_Whitman