Serial Killers with an Abnormally High or Low IQ / Intelligence

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Murder is a truly abhorrent act; so unforgivable, so shocking and so primal in its execution, that surely any civilised, modern and/or educated person in our enlightened world - where knowledge is power, information is key and our glorious grey matter is held as highly as gold - must see murder as an act committed solely by those with an abnormally low IQ? Surely all killers are a bit thick? Aren't all murderers missing a few vital cogs? And doesn't every serial killer put a big 'X' in crayon where there name should be? Well, no. 

According to a study into the IQ levels of 4086 of the world's most prolific serial killers by Radford University - a PDF of the study is attached here - there is a very definite correlation between a serial killer's IQ level and the method they use to kill. 

Before we start, let's put IQ levels into context. According to IQ Research, the average IQ of a British person is 100, an American is 98, with a score from 90 to 105 considered "average intelligence". And yet, the average IQ of a serial killer was 94.7 - a surprisingly average score. Which is not to say that all of them were stupid. Yes, many had subnormal IQ's, most had average IQ's, but quite a few were blessed with impressively high IQ's. But that begs the question, why did they end up a serial killers? 

As always, this is not a comprehensive or complete list, and will be updated as and when new data comes to light, if you have any new info, share it via my Twitter account @mmiletours. Mx

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​Serial Killers & Murderers with the Highest IQs

1. Nathan Leopold IQ 210
2. Richard Lobe IQ 169 
3. ​Ted Kaczynski, IQ 167
4. Charlene Williams, IQ 160
5. Kristen Gilbert, IQ 152
6. Andrew Cunanan, IQ 147
7. Jeffrey Dahmer, IQ 145
8. Dr Harold Shipman, IQ 140
9. Rodney Alcala, IQ 135
10. Edmund Kempner, IQ 136 & 145​​

Leopold & Loeb; two privileged University students attempted to pull off the "perfect murder" as a demonstration of their supposed intellectual superiority by kidnapping and murdering 14-year-old Robert Franks in Chicago in May 1924 and get away with it. The Leopold & Lobe story was fictionalised in the 1948 film Rope directed by Alfred Hitchcock. 

Ted Kaczynski dubbed the “Uni' Bomber” entered the prestigious Harvard University at just 16 years old, graduated at 20, with a PHD in Mathematics and was the University of Berkley’s youngest professor. Ted Bundy graduated with a BA in Psychology and expertly defended himself in court, having taught himself law. And Nathan Leopold & Richard Lobe, who kidnapped and murdered teenager Robert “Bobby” Franks in 1924, believing they were “Nietzschean supermen” whose vast intellects entitled them to ‘kill for the thrill’ and evade capture", had IQ's of 169 (Richard Lobe) and 210 (Nathan Leopold)*... and yes, they were caught, unsurprisingly they were outwitted by their own arrogance.

​Other serial killer IQ's include: Ted Bundy (136), Joel Rifkin (129), Raymond Morris (120), John Wayne Gacy (118), David Berkowitz (118), John Reginald Christie (128), Ed Gein (106), David Copeland (126), Kenneth Bianchi “Hillside Strangler” (116), Gary Heidnek (148), David Carpenter “The Trailside Killers” (125), Carroll Edward Cole (152), Juan Corona “The Machete Murderer” (130), Michael Gary Hilton (120), Patrick McCullough (120), Derek Ernest Percy (122), Lesley Eugene Warren “Babyfaced Killer” (115), Arthur Shawcross (86/105/107 tested 3 times) and Warren James Bland (107). An IQ of roughly 98-100 is considered normal, so the following fall below that; Richard Chase “Vampire of Sacremento” (95), Robert “Willie” Pickton (86), Jessie James Cummins (81), Gary Ridgeway “Greenriver Killer” (81), Daniel Blank (85), Tommy Lynn Sells “Coast to Coast Killer” (80), Henry Lee Lucas (76-89), Glen Edward Rogers “The Casanova Killer” (76), William K Sapp “The Dreaming Demon” (73), Alton Coleman (72) and John Straffen (tested twice, IQ of 58 and 64). It’s worth noting that an IQ of 70 is classified as retarded. Thanks to University of Radford for the additional information. 

Although not a serial killer, Derek Bentley - who was infamously tried, executed and posthumously pardoned for the murder of British Policeman Sidney Miles in 1952, a crime which brought about the abolition of capital punishment in the UK - had an IQ of just 66. And - although technically a spree-killer - Martyn Bryant who mass-murderer who killed 35 people in the Port Arthur massacre in 1996 - also had an IQ of just 66. 

But what difference should a serial killer's IQ make? Surely killing is killing? Well, not quite. According to Radford University's study into 4086 serial killers across the world, the level of IQ a serial killer has, often defines what method is killing they are likely to prefer. What follows is a list of preferred methods of killing, by serial killers, how many and their average IQ. 

• Death by Bomb, 3 serial killers, IQ 140.3
• Death by Strangulation & Gun, 6 serial killer, IQ 105.8
• Death by Strangulation & Bludgeoning, 8 serial killers, IQ 108.8
• Death by Poisoning, 1 serial killer, IQ 100.0
• Death by Stabbing & Gun, 24 serial killers, IQ 96.0
• Death by Strangulation, 40 serial killers, IQ 96.9
• Death by Stabbing, 23 serial killers, IQ 92.7
• Death by Gun, 59 serial killers, IQ 90.8
• Death by Strangulation & Stabbing, IQ 13 89.5
• Death by Stabbing & Bludgeoning, 11 serial killers, IQ 85.5
• Death by Bludgeoning & Gun, 10 serial killers, IQ 82.2
• Death by Bludgeon only, 10 serial killers, IQ 78.5 

​​Death by bomb (a technical skill) or strangulation (a very manual "hands-on" method of murder) all scoring IQ levels of "above average intelligence", with the bulk of stabbing, shooting and bludgeoning scoring "below average intelligence". ​

And yet, as seen in the Broad Motives of Serial Killers chart, 48% murder for enjoyment, which accounts for the bulk of those with high IQ's, where as the other 52% - with average or below average IQ's - kill for personal needs. 

If you'd like to learn more about the IQ of serial killers, read more at Business Insider, or download Radford University's comprehensive study here, as it goes into great detail into serial killers as defined by - not just IQ - but also by age, geography, wealth, ethnicity, era, how many were in military service (a topic Murder Mile touched on here).

And in case you're wondering, how safe am I, in my own country, with all these serial killers running around - regardless of how smart or dumb they might be?

Well, you'll be fine, just as long as you live in Norway, Sweden or Denmark (see Serial Killers by Country chart), they're not even listed. Where-as the United States? You must be bricking it.

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If you "enjoyed" this blog post, why not take a peek at; Serial Killers as Siblings, Serial Killer's Nicknames, Serial Killers Who Were Never Caught, London's Deadliest & Often Forgotten Disasters, Are More Serial KIllers Born During a Full Moon, Killer's Birthdays / Star Signs, Serial Killers Who Were On TV, Celebrities Who Have Killed, London's Railway of Death, Serial Killers as Kids and the World's Weirdest Death Rituals. ​​

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Michael J Buchanan-Dunne is a writer, crime historian and tour-guide who runs Murder Mile Walks, a guided tour of Soho’s most notorious murder cases, hailed as “one of the top ten quirky & unusual things to do in London” and featuring 12 murderers, 3 serial killers, across 15 locations, totalling 75 deaths, over just a one mile walk.