How was Edmund Kemper caught?

He turned himself in. In April 1973 he called police from a Colorado phone booth to confess. He was convicted of eight counts of first-degree murder in Santa Cruz County in 1973.

What was Edmund Kemper’s IQ?

145, according to the Radford/FGCU Serial Killer Database. An earlier test recorded 136.

What is the average IQ of a serial killer?

Below the general average. The Radford/FGCU Serial Killer Database puts the mean at about 94 to 95 and the median at about 86 to 89.

The MythNo. 01

An IQ of 145 turned himself in.

Santa Cruz, California1972–1973

Stat · No. 01

IQ against time free

KemperIQ 145turned himself in, under a year
RidgwayIQ 8519 years free

Bar length is time free

Data table

IQ against time free
Measure	Value	Kind	Note
Kemper	IQ 145	Count	turned himself in, under a year
Ridgway	IQ 85	Count	19 years free

Drawn from: Radford/FGCU Serial Killer Database · People v. Kemper, 1973

The case

Santa Cruz, California · 1972–1973

Edmund Kemper. Santa Cruz, California, 1972 to 1973. Eight people killed: five young women and a fifteen-year-old girl he picked up hitchhiking, then his mother and her closest friend. All along he drank at a police bar. In April 1973 he called police from a Colorado phone booth to confess.

The mechanism

Does intelligence decide which killers get caught?

Intelligence does not predict who gets caught. Gary Ridgway tested at 85 and stayed free nineteen years. The men who lasted had something else: victims nobody reported, no biological evidence, several jurisdictions, and the discipline to stop. None of that requires brains.

The rule

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

The record

No. 01 · The Myth

Sources

Radford/FGCU Serial Killer Database, Kemper case file (Aamodt, 2004) — Kemper IQ 145
02
Prothero & Smith, ‘Defending Gary’ (Wiley, 2006), p. 150 — Ridgway IQ 85, tested for the defense by Dr. Craig Beaver
- Primary recordJossey-Bass (Wiley)
People v. Kemper, Santa Cruz County Superior Court — jury verdict Nov 8, 1973, eight counts of first-degree murder (court file not online; verdict as reported by the SFSU Bay Area Television Archive and Lookout Santa Cruz, Jul 10, 2024)

Transcript56.4 s

0:00
Claim
An IQ of 145 turned himself in.
0:04
Case
Edmund Kemper. Santa Cruz, California, 1972 to 1973. Eight people killed: five young women and a fifteen-year-old girl he picked up hitchhiking, then his mother and her closest friend. All along he drank at a police bar. In April 1973 he called police from a Colorado phone booth to confess.
0:27
Mechanism
Intelligence does not predict who gets caught. Gary Ridgway tested at 85 and stayed free nineteen years. The men who lasted had something else: victims nobody reported, no biological evidence, several jurisdictions, and the discipline to stop. None of that requires brains.
0:48
Rule and source
The genius killer is a movie. The data says average. Source: Radford, F-G-C-U Serial Killer Database.

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

Questions

Who did Edmund Kemper kill?: Eight people in Santa Cruz, California, in 1972 and 1973: five young women and a fifteen-year-old girl he picked up hitchhiking, then his mother and her closest friend.
How was Edmund Kemper caught?: He turned himself in. In April 1973 he called police from a Colorado phone booth to confess. He was convicted of eight counts of first-degree murder in Santa Cruz County in 1973.
What was Edmund Kemper’s IQ?: 145, according to the Radford/FGCU Serial Killer Database. An earlier test recorded 136.
What is the average IQ of a serial killer?: Below the general average. The Radford/FGCU Serial Killer Database puts the mean at about 94 to 95 and the median at about 86 to 89.