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The least intelligent serial killers

Henry Lee Lucas in court
Henry Lee Lucas Image – Image Credit: Everett Collection Inc / Alamy Stock Photo | Above: Henry Lee Lucas confesses to hundreds of murders, during his trial in the mid-1980's.

As we've previously explored in our article 'Who is the most intelligent serial killer?', the average person has an IQ of around 95-105. The average serial killer, according to The Serial Killer Information Center, has an IQ of 94.5.

But which of them ranks below that average? Let’s find out the answer to the question of who the least intelligent serial killers were.

Fred West

Illiterate and with little to no curiosity about the wider world, Gloucestershire rapist and killer Fred West was only really interested in sex and sexual sadism. He never really went to school and suffered from a series of serious head traumas, many of which he sustained while attempting to sexually assault local women.

Aileen Wuornos

IQ tests are a half-decent indicator of intelligence but are still flawed. Still, anyone scoring 81 on an IQ test is very rarely going to be the most intelligent person in the room. Although it is widely thought that when Aileen Wuornos scored 81 on her tests, she did so while intentionally answering questions incorrectly to delegitimise them. Such was her disdain for being made to take them.

Either way, history’s most infamous female serial killer is still widely regarded as having been of pretty low intellect. It's difficult to say how much of that was down to her incredibly disruptive, chaotic and abusive childhood

Henry Lee Lucas

Henry Lee Lucas was not an overly smart man. Despite having no education and growing up in a shack watching his sex-worker mother’s exploits every day, he was able to pull the wool over the police’s eyes for long enough as an adult.

How many people he killed precisely is unknown. To obfuscate the true number and remain a useful asset to the authorities, he constantly confessed to murders all across America. Police, keen to tie up some open cases, were only too happy to accommodate him and listen to his tall tales. During these confessions, Lucas was treated much better than a common killer rotting in jail.

Ottis Toole
Ottis Toole | Ottis Elwood Toole Image – Image Credit: Associated Press / Alamy Stock Photo | Above: Ottis Elwood Toole (left) watched courtroom spectators as he was fingerprinted by an unidentified court bailiff (right) after he was sentenced to death on

Ottis Toole

If you’re going to be ‘The Smart One’ in a gruesome twosome and you’ve got an IQ of 84, you need to find yourself someone of seriously low intellect to partner up with. Henry Lee Lucas recruited Ottis Toole, an equally vicious psychopath with a full nine IQ points less than him.

Of course, an IQ rating doesn’t impact a person’s desire or ability to commit a crime, but even aside from his score, Ottis Toole was widely regarded as being a simpleton.

Gary Ridgway

Despite having an IQ in the low 80s and barely making his way through school, Gary Ridgway was an incredibly prolific serial killer. Known as ‘The Green River Killer’, he was convicted of killing 49 victims, with the true figure perhaps being closer to 90.

It seems as if the Washington State-based murderer concentrated what few smarts he did have into his killing career. He may not have been booksmart, but he was organised and personable. This allowed him to win trust and cover his tracks.

Derrick Todd Lee

Between 1992 and 2003, ‘The Baton Rouge Killer’ murdered seven women with extreme violence. He did so while having an IQ of 65, which is an extremely low score.

However, authorities investigating him were hardly excelling in the smart stakes. Lee was a strong suspect in the case but was frequently ignored because profilers had decided that the killer was a white man. Lee was black and, as such, didn’t fit the profile.

DNA evidence finally saw him apprehended and convicted. Despite his IQ being below the usual threshold for being able to stand trial.

Dennis Rader

Between 1974 and 1991, a man known only as ‘The BTK Killer’ (‘Bind, Torture, Kill’ - a name he gave himself) terrorised Kansas, killing ten people in some of the most brutal home invasions imaginable. It wasn’t until 2005 that the world learned his given name, Dennis Rader.

Rader spent 14 years in the clear, effectively having gotten away with his awful crimes.

Not so stupid, then? The trouble is, he couldn’t leave it alone. In 2004, presumably while bored and seeking the thrill of reliving his evil past, he began writing letters to police, taunting them.

Although his eventual conviction was largely due to a DNA match, Rader had made himself a marked man by sending floppy disks containing documents to police for them to read. Disks containing metadata which pointed police directly to him.

Now, it could be tempting to forgive Rader’s ignorance. After all, who knew much about metadata in 2005? The thing is, he only started sending floppy disks after asking if it was safe. ‘Can I communicate with Floppy and not be traced to a computer. Be honest,’ he wrote.

Staggered by his trust, Wichita police lied and then found out BTK’s identity. It was Dennis Rader, a man who’d been almost ludicrously stupid in getting caught in the manner in which he did.