Essentially, he said that serial killers on average committed their first murder at the age of 28, saying that a large number of serial killers active in the late 70s were raised by men suffering from the trauma of the war in World War II, having been raised in the early 50s.
Plausible, but not provable.
It's going to be nearly impossible to determine anything concrete about the high rate of serial killers during that period.
This report points to the late 1980s as having the highest rates of both active serial killers and serial killer victims. This immediately throws into question the conclusion of the expert. What data are they basing the late '70s claim on? Is their data more accurate than this data?
Another issue is that serial murder data is subject to many inaccuracies. The basic problem is that lots of murders remain unsolved. This article (I read this incorrectly in my original post. The rate of unsolved murders has been increasing, not decreasing. I still think serial murderer data is subject to many inaccuracies, but clearance rate of homicides is probably much less of a factor.)
A third issue is increased awareness of serial murder. To draw an analogy, the rate of prostate cancer in the USA jumped a few times since the '50s. This wasn't because more people were getting cancer. It was due to surgical techniques and blood testing advancing. As the tools to detect cancer became more sensitive, the rate of identification went up. In the same way, as awareness of serial killers increased it was identified more often.
Then there's the issue of what causes a person to become a serial murderer. I prefer to rely on the conclusions of psychologists and psychiatrists rather than the FBI and criminologists. Imo, the criminal justice industry performs poor science. As far as I can gather from some lit review, serial killers are an extremely small population that is composed of psychopaths and/or people with personality disorders (there's some discrepancy in the labeling). Far more people have these traits who do not murder. There is some commonality in other exposures (animal violence, bedwetting) but they are by no means predictive. By parallel, people who smoke are much more (20-30x) likely to develop lung cancer, but lots of smokers don't get lung cancer and lots of non-smokers get lung cancer.
Finally, it's only by looking at the data right now that we see a bump in serial killer frequency in the 70s-80s. Serial killers can often be found decades after their murders are committed, and the number of serial killers active in the last 15 years will only increase (but by how much).
It's certainly plausible that WWII trauma affected children and increased the rate of serial murderers, but there's almost no way to take that from a plausible opinion to one supported by science.
One prominent theory that is best laid out in Ginger Strand's "The Killer on the Road" is that the construction and completion of the Interstate Highway System led to the proliferation of serial killers in the 1970s and 80s. Construction of the Interstate began in 1956 and the system began to really come together by the mid 70s. Nebraska became the first state to complete all of their portions in 1974. The Interstate enabled killers to move from place to place with greater ease and anonymity in an era with negligible forensic capabilities (the first application of DNA in a case was in 1985).
The highway system greatly accelerated the growth of the trucking industry in the 50s and 60s, an industry that gave killers a reason to constantly be moving from place to place. Transients, hitchhikers, and truck stop prostitutes supplied killers with easily accessible victims. The FBI points out this pattern in a blog post on their site: "A long-haul driver can pick up a prostitute at a truck stop in Georgia, rape and murder her, and dump her body on the side of the road in Florida later that day. The victim has no connection to the area where she was found, and there may be no forensic evidence to collect because the crime was committed hundreds of miles away"
While the Interstate theory doesn't explain all serial killings, it does help explain a motive and means for some of the overall spike in serial killings during that time period.
OP, it would be worth x-posting this question to /r/AskSocialScience; they may be able to cite or recommend some studies for this.
Isn't there a theory about lead in gas making people more violent? I rarely hear about it so I'm not sure if it's a conspiracy theory of something more scientific.
This would involve a complex range of questions:
Why do people become killers and serial killers in the first place. Is it nature or nurture?
Is there any evidence that home environment contributes significantly- as in over and above other factors?
Of all the serial killers known, how many of them had fathers who went to war?
Of those that went to war, which of them saw active duty?
Did domestic violence also feature in their homes?
Of the children of war veterans who did not become serial killers, do they now feel that their father's behavior during their upbringing was somehow violent, draconian, etc.?
As the child of a war veteran myself, I always felt that my father's psychotic episodes stemmed from his own brain chemistry and also the time of deprivation during the Great Depression. Many of the people who fought in WWII may have experienced great hardships (with nutrition, education, love, affection) growing up due to the Great Depression as well. When a family has severe money worries over a long period, it stuffs up your mental health.
Do you have a link to the podcast? Which episode was this?
This is an interesting idea thats never been really discussed. Whether we are referencing American WWII veterans coming home to the US after the war, or Holocaust survivors coming to the U.S. or refugees, or SS/Nazi's themselves after the war, Ive always wondered, how the fuck could any of them just settle into a regular life again? You couldnt. No normal person could given what all of them saw or did during the war.
I've had a theory for years that the cause of this very spike in the 70s & 80s could possibly have something to do with drug use in the 60s & 70s. Could bad trips from Hallucinogens have something to do with it? Charles Manson used drugs [lsd, speed, etc] to gain more control over young, impressionable minds. Just a theory I've contemplated quite a bit.
I would be as likely to blame it on women's liberation movement as I would anything. But then again, it is probably only one of many small factors, or not one at all. Why would I lay that out as a driving force? For the first time, women got the deserved care that had been lacking when working as prostitutes or homeless, and these are common victims.
Or maybe I'm just talking out of my ass.
population increase as well. More people, more murderers