Since a dramatic peak in the 1980s, serial killers in the U.S. like Ted Bundy and Jeffrey Dahmer have been in decline for three decades. Experts have a few theories that can help explain why.
Later researchers found a coding error and pointed out that Mr Levitt had used the total number of arrests, which depends on the size of a population, and not the arrest rate, which does not. Others pointed out that the fall in homicide started among women. No-fault divorce, rather than legalised abortion, may have played a bigger role.
Seems to have been debunked: https://www.economist.com/finance-and-economics/2024/03/21/why-freakonomics-failed-to-transform-economics