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The MythMyth

The genius killer is fiction. The IQ record says average.

The short answer

Are serial killers smarter than average?

No. The FBI’s 2008 serial murder monograph lists the idea that serial killers are all insane or geniuses as a myth, and says they range in intelligence from borderline to above average.12 A Radford University page last updated in 2012 gives a median IQ of 89.0 for 202 serial killers.3 The Radford/FGCU database’s 2016 report gives 86.0 for 271.4

Stat · The Myth

Two scores and the median

  1. Kemper, Radford student summary145
  2. Database median, 201686.0
  3. Ridgway, his lawyer's book85

Radford/FGCU Serial Killer Database, September 4, 2016: average IQ 94.5, median 86.0, N = 271

Data table
Two scores and the median
MeasureValueKindNote
Kemper, Radford student summary145Count
Database median, 201686.0Count
Ridgway, his lawyer's book85Count

What does the FBI say about the genius killer?

In 2008 the FBI published “Serial Murder: Multi-Disciplinary Perspectives for Investigators.”25 The report says it grew out of a symposium held in San Antonio, Texas, in 2005, attended by 135 experts.14 It lists seven common myths about serial killers.15 The sixth is that serial killers “have either a debilitating mental condition, or they are extremely clever and intelligent.”1

The report answers both halves. As a group, it says, serial killers suffer from a variety of personality disorders, including psychopathy and antisocial personality, but most are not adjudicated as insane under the law.1 It adds that the media “has created a number of fictional serial killer ‘geniuses’, who outsmart law enforcement at every turn.” Like other populations, it says, serial killers “range in intelligence from borderline to above average levels.”1

What do the IQ records show?

A Radford University page last updated on September 16, 2012 describes serial killers, taken as a whole, as appearing to be of normal IQ. It reports a median of 89.0 and a mean of 95.1 for 202 serial killers.3 The Radford/FGCU database’s September 2016 report gives a median of 86.0 and an average of 94.5 for 271 serial killers.4

Mike Aamodt of Radford University wrote the September 2016 statistics report of the Radford/FGCU Serial Killer Database.4 The report says Radford partnered with Florida Gulf Coast University in 2012 to keep the database updated, and that as of September 4, 2016, the database held information on 4,743 serial killers and 13,105 victims.46

A Radford page last updated on September 16, 2012 reports IQ information on 202 serial killers, with a median of 89.0 and a mean of 95.1.3 The September 2016 report has IQ figures for 271 of the database’s 4,743 serial killers, with a median of 86.0, an average of 94.5, and scores from 54 to 186.4

The 2012 page carries its own caution: extreme scores draw more publicity, and there is a motive to score low, especially below 70.3 The database itself was built from information collected by Radford University students from sources including prison records, court transcripts, media sources, true crime books and the Internet.6

Did a high IQ protect Edmund Kemper?

Santa Cruz, California, 1972 to 1973. Eight people were killed: Mary Ann Pesce, Anita Luchessa, Aiko Koo, Cindy Schall, Rosalind Thorpe, Alice Liu, Clarnell Strandberg and Sally Hallett.78 The first six, one of them 15, had accepted rides.78

Edmund Kemper was convicted of killing all eight. Clarnell Strandberg was his mother, and Sally Hallett was her friend.78 A 2004 case summary compiled by Radford University students lists his IQ as 145.9 A 2023 feature on the case says he scored 145 on an IQ test at Atascadero State Hospital.7

In April 1973 he called Santa Cruz police from a phone booth in Pueblo, Colorado, and confessed.810 Police who knew him did not believe him at first.89 In November 1973 a jury convicted him on all eight counts of first-degree murder.78 His own phone call ended his freedom.79

How did Gary Ridgway stay free for 19 years?

The deaths of at least 48 women were linked to the Green River case, which began in 1982.1112 For years, detectives lacked the evidence to build a case against Gary Ridgway.1314 In November 2001, DNA testing of a saliva sample taken in 1987 led to his arrest.1214 His defense lawyer’s book says his IQ tested at 85.17

On July 15, 1982, Wendy Lee Coffield, 16, was found in the Green River in King County.1113 Within a month, Debra Lynn Bonner, Marcia Faye Chapman, Opal Charmaine Mills and Cynthia Jean Hinds were also found in or along the river.1112 The deaths of at least 48 women were eventually linked to the case.1112

Mark Prothero, one of Gary Ridgway’s court-appointed defense lawyers, wrote “Defending Gary” with Carlton Smith.1215 The book says his IQ, measured on unwritten tests, “came out to be 85.”17 Ridgway passed a polygraph examination in 1984.1416 In 1987 investigators took a saliva sample from him, and it waited 14 years for DNA testing able to read it.1214

He was arrested on November 30, 2001, as he left his job in Renton, where he had worked as a truck painter for more than 30 years.11314 Nineteen years had passed since the first deaths. What caught him was the 1987 saliva sample.1214 On November 5, 2003, he pleaded guilty to 48 counts of aggravated first-degree murder.1112

The rule

The genius killer is a movie. The data says average.

The cases

Where this shows in the record

Questions

Are serial killers legally insane?

Most are not. The FBI’s 2008 serial murder monograph says serial killers as a group suffer from a variety of personality disorders, including psychopathy and antisocial personality, but that most are not adjudicated as insane under the law.12

Why are there two different Radford IQ figures?

They come from different dates. Radford says its serial killer project began in 1992 and that its data are added and revised on a continual basis.6 A page last updated on September 16, 2012 covers 202 serial killers, with a median of 89.0. The September 2016 report covers 271, with a median of 86.0.34

What was Edmund Kemper’s IQ?

A 2004 case summary compiled by Radford University students lists Edmund Kemper’s IQ as 145, and a 2023 feature on the case says he scored 145 on a test at Atascadero State Hospital. Neither names the test. He confessed by phone in April 1973 and was convicted on eight counts that November.789

Who built the Radford/FGCU Serial Killer Database?

Radford University, from information its students collected.6 The September 2016 report says Radford partnered with Florida Gulf Coast University in 2012 to keep the database updated and publish annual summary reports. Mike Aamodt of Radford wrote that report, which counted 4,743 serial killers and 13,105 victims.4

How was Gary Ridgway identified?

By DNA. Investigators took a saliva sample from Gary Ridgway in 1987. New DNA testing of that sample led to his arrest on November 30, 2001, and on November 5, 2003, he pleaded guilty to 48 counts of aggravated first-degree murder.11121314

The record

The Myth

Sources

  1. FBI Behavioral Analysis Unit-2, National Center for the Analysis of Violent Crime, “Serial Murder: Multi-Disciplinary Perspectives for Investigators,” ed. Robert J. Morton (FBI, 2008): seven myths, including that serial killers are all insane or geniuses; intelligence from borderline to above average; most not adjudicated insane; 2005 San Antonio symposium of 135 experts; Ridgway a truck painter for 32 years

  2. FBI, “Serial Murder - July 2008” (fbi.gov document page): publication date of the monograph

  3. Mike Aamodt, “Serial Killer IQ” (Serial Killer Information Center, Radford University, last updated September 16, 2012): IQ information on 202 serial killers, median 89.0, mean 95.1; serial killers taken as a whole appear to be of normal IQ; caution on extreme scores

  4. M. G. Aamodt, “Serial Killer Statistics” (Radford University/FGCU Serial Killer Database, September 4, 2016): IQ N 271, average 94.5, median 86.0, range 54 to 186; 4,743 serial killers and 13,105 victims; FGCU partnership 2012; the FBI’s 2005 symposium in San Antonio

  5. Office of Justice Programs, NCJRS Virtual Library, abstract record for “Serial Murder: Multi-Disciplinary Perspectives for Investigators,” NCJ Number 223848 (undated record): date published 2008; the seven myths the symposium discounted

  6. Mike Aamodt, “Project Description” (Serial Killer Information Center, Radford University, last updated September 4, 2016): project began in 1992; data added and revised continually; 4,743 serial killers; database built from information collected by Radford students

  7. Benjamin H. Smith, “Ed Kemper: The Horrifying True Tale Of The Santa Cruz ‘Co-Ed Killer’” (Oxygen, April 13, 2023; first published October 9, 2018): victims’ names, IQ 145 at Atascadero, Pueblo call, conviction on eight counts November 8, 1973

  8. Biography.com Editors, “Edmund Kemper” (Biography, updated October 3, 2023): victims’ names, the April 1973 call from Pueblo, police disbelief, eight counts of first-degree murder, guilty in November 1973

  9. Radford University students, “Edmund Emil Kemper III” case summary (Radford University Department of Psychology, course file “Kemper, Ed - 2004”; latest entry 2004): IQ 145; repeated calls from Pueblo; arrested April 24, 1973

  10. San Francisco State University, DIVA, “Investigating Edmund Kemper” (KPIX news footage, April 25, 1973): confession from a phone booth in Pueblo, Colorado

  11. King County Sheriff’s Office, “Green River homicides investigation” (King County, undated, accessed October 8, 2026): first victims found July 1982; at least 48 women linked; guilty plea to 48 counts, November 5, 2003

  12. David Wilma, HistoryLink.org Essay 4262, “Gary Leon Ridgway pleads guilty to murdering 48 Green River Killer victims on November 5, 2003” (posted November 5, 2003): plea date and count; bodies found in and along the river within a month; DNA sample collected in 1987; Mark Prothero among court-appointed defenders

  13. HistoryLink Staff, HistoryLink.org Essay 3648, “Police arrest Green River Killer suspect on November 30, 2001” (posted December 2, 2001): arrest date; Wendy Lee Coffield, 16, found July 15, 1982; detectives had not found adequate evidence to build a case

  14. Ian Ith, Steve Miletich and Duff Wilson, “Detectives’ case hinges on 14-year-old saliva sample in Green River arrest” (The Seattle Times, December 1, 2001): 1987 saliva sample, new DNA testing, arrest at work, painter for more than 30 years, lie-detector test reported by Smith and Guillen, prosecutors lacked evidence for trial

  15. Wiley, product page for Mark Prothero with Carlton Smith, “Defending Gary: Unraveling the Mind of the Green River Killer” (Jossey-Bass, e-book, ISBN 978-0-787-98508-0, April 2006): Prothero a co-lead defense attorney for Gary Ridgway; written with Carlton Smith

  16. Steve Miletich, “Ridgway stayed cool in interview 19 years ago” (The Seattle Times, February 10, 2004): polygraph passed in 1984

  17. Mark Prothero with Carlton Smith, “Defending Gary: Unraveling the Mind of the Green River Killer” (Jossey-Bass, 2006), p. 150, read through Google Books search inside the book: Ridgway’s IQ on unwritten tests came out to be 85; average intelligence is 100

Educational analysis. Adjudicated cases only. Victims named with respect.