Psychological criminal profiling.

[Mr.Obvious]

And then on page ten, it says:

According to the table, most seem to be male. But only 52.5% seem to be white. In a country with 60% whites, that is not disproportionate. And definitely not in exhuberant fashion. If anything, it's less than we'd expect. Of course, it could still be there are relatively 60% or higher white serial killers in the grander serial killer population. But that they are more apt at getting away with it because they, on average, have more means to (as whites in America are relatively less poor and might very well be concidered less as possible killers through bias or there might be other things at play.) Or maybe not. Dark numbers are hard to work with.

So on the whole, I don't think that source builds your case. (Edit: ) Also because of the too vague definition. I don't think the Numbers comparing serial Killers and coming up with relatively less in the White subgroup are even accurately comparing 'serial killers'.

(Edit: I found an old source saying 61% in America were whites. But it turns out, another source maybe with a different definition, says it's up to 77% I don't know the exact number, though they seem to be the majority.)

If you look at what I was citing, you'll see that the proportion of white to black serial killers has changed in recent decades. Several decades ago, it was something like 70+% were white. I posited that this is because the FBI's current definition has not always been in use. The man who coined the term meant it to describe people who got some sort of sexual pleasure out of killing, the cooling off period, etc. I cited this study specifically because I thought it called into question all of the things we've been discussing, not because I thought it built a solid case for anything.

Let's take South Africa for example, about 1 in 10 people are white in South Africa. Yet, most of their serial killers are white.

https://en.wikipedia.org/wiki/List_of_se...uth_Africa

I've also realized that here we have the unusual problem of sorting out whether Hispanics who identify as white are counted as white or Hispanic in these studies. It's all quite convoluted. Still, I think we all concede the point that racial profiling is problematic. I simply personally think you're more likely to be looking for a white dude if you're looking for a serial killer, depending of course on the M.O., which can often point to a woman.

Even if they were 70% back then, I don't think it would be disproportianate in the US.
Looking at Wikipedia, but seeing it's sources check out at first glance, the subgroup size seems to be congruent. Whites went from almost 90% of the US population to 72% of the population in the last century. Agreed that the 'Non hispanic white' has me for a loop, looking at it at surface value. But that has declined from almost 90% to 63%. This last one would even be perfectly proportionate to the findings in the first source.
(https://en.wikipedia.org/wiki/Historical...erenceB-17 )
(https://www.census.gov/population/www/do...ps0076.pdf )
But yes, I agree. That first source is a bit vague and doesn't seem to fit what you or I would concider a serial killer, so I don't think that first source would be reliable.

Regarding serial killers in South Africa, however. The only source I can find saying it's disproportionate all is a single article on IOL, which is referenced in your Wikipedia link. This one: http://www.iol.co.za/news/crime-courts/m...es-1766044 . Problem however is that when I looked at it, it seemed to be just one mention without reference to sources and not even a mention of how big the sample size is or how big the disproportion. This kind of thing doesn't bode well for the validity of the claim.

That's why when looking a bit deeper, I found the following on this: http://www.news24.com/MyNews24/South-Afr...s-20150113

A recent article titled “Most SA serial killers are white males” is an example of media propagating this myth.  Although it went on to say that “proportionally more white men are serial killers than any other racial group”, the heading was clearly misleading and could be argued that it was deliberate considering that only 1 in 5 readers go on to read the full article.
Of the total number of convicted serial killers in South Africa, approximately 7 in 10 are black, 1 in 10 are coloured and 2 in 10 are white, an overrepresentation.  But these are historical figures.  Earlier I mentioned that there has been a clear racial shift post-Apartheid which I’d like to explain by using ratios of white serial killers to total serial killers over a series of time periods:
·         Convicted white serial killers - pre 1994– 5 in 10
·         Convicted white serial killers 1995 to 2004 – 2 in 10
·         Convicted white serial killers 2005 to date – 1 in 10
·         Convicted white serial killers 2009 to date – 0 in 10

Now, the above source doesn't link to the propper sources either. So it might be pulling stuff out of it's ass for all I know. But if we say that, we have to conced that possibility of the Original IOL source as well. The news24 source does seems to agree, however, that the south african serial killers were 'historically' unproportionaltly white.
But seeing as this South African  story seems at best to be an anomaly, I think it's important to keep an open mind on the possible explanations behind this number. It could be, as your hypothesis says, that there is some underlying difference in lifestyle. Personally, I find it more likely and more in line with the known data in other countries and population groups, that there is some fault in the measurement of the data. I can for instance imagine South Africa having less than stellar forensics departments in comparison to Western countries, creating a basis for faulty measurement. If, in addition to that, the white population is richer and more powerful, they might also historically get/got more devotion of the police corps, giving them disproportionate time and effort in examining the cases. Perhaps a black serial killer operating in a black ghetto in South Africa has/had less chance of getting caught because the police corps investigate less of their time and effort in bringing the murderer of 'poor folk' to justice. It's just a working hypothesis, but I find it more in line seeing as South Africa seems to be the only 'outlier'.

According to this source, which I can't claim it's validity either, on page 43 it says in South Africa serial killers are primarily black:
https://books.google.nl/books?id=HoWMab7...te&f=false
Which could still leave open a disproportionatly high white-serial killer rate in South Africa. But it doesn't mention it. And seeing the above, I kind of doubt it.

What it does mention is that in primarily black communities, serial killers tend to be black, in primarily hispanic, they tend to be hispanic, ... And

The only reason most serial killers in the United States are white is because most of the population in the United States is white.

Racial profiling at this point would be as useful, it seems to me, as going to China and investigating a serial killer there and working off the assumption that the killer probably has black hair. It's probably true, but with a larger subgroup, it doesn't help your investigation either. Profiling would only 'work' if your subgroup you focus on is smaller, it seems to me. You probably are looking for a male, because about 90% of serial killers are male and only 50% of the population is male. If 95% of your population has black hair, however, saying the serial killer is most like to have black hair doesn't help your case. Same goes for skin color.