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.
Could it be that not as many potential serial killers are being born? I believe there is a link between criminality and childhood abuse. Less unwanted kids are being born. Less abuse. Less criminals of all kinds, including serial killers.
CSI type pop culture television has taught basically everyone on the planet that trace evidence always gets left behind and nobody can hide from DNA. Nowadays through genealogy they don't even need a direct DNA match.
The Long Island serial killer case that broke recently is a good example, they got evidence out of pizza crust he left in a garbage can outside his office. Evil piece of shit he is.
This is the answer. The logistics of staying off camera and getting around without leaving a digital signature is much more complicated. In the 70s you could buy a bus pass with cash and disappear for a few days and nobody would know and you'd never be on any list of suspects. Now you need to set up fake cell phone activity and get an alibi on camera and put on disguises in a dive bar bathroom and shit. Very difficult to get "lost" for more than a few hours if you are working alone and operating anywhere near civilization.