"It's certainly not an ordinary suicide note," Dr. Phil Resnick, director of forensic psychiatry at University Hospitals Case Medical Center in Cleveland, told ABCNews.com after looking at the writings.
"He doesn't talk much about his own dilemmas of being in prison or why he's taking his own life," Resnick said. "It's more of a final statement of contempt for the American style of life and I think the other thing he emphasizes is his own superiority, that he has guile and can take advantage of people who are naive and trusting of him."
Dr. Stephen Montgomery, a forensic psychiatrist at Vanderbilt University Medical Center in Nashville, said the writings show intelligence and a clear understanding that Keyes knows his behavior was wrong.
"He's writing this so that people will find it and talk about it and further magnify his own self worth," Montgomery told ABCNews.com. "And, of course, it has no remorse, no regard for human life or the victims and that fits with that type of psychopathic personality."
Montgomery also said the notes were reminiscent of a famous movie killer, "The butterflies and moths sort of evoke 'The Silence of the Lambs' type of killer."
Keyes ends the writings with the haunting lines, "Okay, talk is over, words are placid and weak. Back it with action or it all comes off cheap. Watch close while I work now, feel the electric shock of my touch, open your trembling flower, or your petals I'll crush."
The FBI said they continue to work closely with state and local law enforcement agencies across the country to identify other Keyes victims.
Parts of the letter are illegible, but this is the full text, as best can be deciphered:
"Where will you go, you clever little worm, if you bleed your host dry?
Back in your ride, the night is still young, streetlights push back the black I neat rows. Off to the right a graveyard appears, lines of stones, bodies molder below. Turn away quick, bob your head to the seat, as straight through that stop sign you roll loaded truck with lights off slams into you broadside, your flesh smashed as metal explodes.
You may have been free, you loved living your lie, fate had its own scheme crushed like a bug you still die.
Soon, now, you'll join those ranks of dead or your ashes the wind will soon blow. Family and friends will shed a few tears, pretend it's off to heaven you go. But the reality is you were just bones and meat, and with your brain died also your soul.
Send the dying to wait for their death in the comfort of retirement homes, quietly/quickly say "it's for the best" it's best for you so their fate you'll not know. Turn a blind eye back to the screen, soak in your reality shows. Stand in front of your mirror and you preen, in a plastic castle you call home.
Land of the free, land of the lie, land of scheme Americanize! Consume what you don't need, stars you idolize, pursue what you admit is a dream, then it's American die.
Get in your big car, so you can get to work fast, on roads made of dinosaur bones. Punch in on the clock and sit on your ass, playing stupid ass games on your phone. Paper on your wall, says you got smarts. The test that you took told you so, but you would still crawl like the vermin you are, once your precious power grids blown.
Land of the free, land of the lie, land of the scheme, Americanize.
Now that I have you held tight I will tell you a story, speak soft in your ear so you know that it's true. You're my love at first sight and though you're scared to be near me, my words penetrate your thoughts now in an intimate prelude.
I looked in your eyes, they were so dark, warm and trusting, as though you had not a worry or care. The more guiless the game the better potential to fill up those pools with your fear.
Your face framed in dark curls like a portrait, the sun shone through highlights of red. What color I wonder, and how straight will it turn plastered back with the sweat of your blood.
Your wet lips were a promise of a secret unspoken, nervous laugh as it burst like a pulse of blood from your throat. There will be no more laughter here.
I feel your body tense up, my hand now on your shoulder, your eyes…Forget the lady called luck she does not abide near me for her powers don't extend to those who are dead.
[illegible words] would that I could keep you, let you be the master of your own fate...knowing full well what's at stake? My pretty captive butterfly colorful wings my hand smears...I somehow repaint them with punishment and tears.
Violent metamorphosis, emerge my dark moth princess, I would come often and worship on the altar of your flesh…You shudder with revulstion and try to shrink far from me. I'll have you tied down and begging to become my Stockholm sweetie.
Okay, talk is over, words are placid and weak. Back it with action or it all comes off cheap. Watch close while I work now, feel the electric shock of my touch, open your trembling flower, or your petals I'll crush."