As Thorn pointed out, mass killer =/= serial killer. Not sure if one is more deranged than another, but serial killers work methodically and over time. Mass killers, while they might plan meticulously, plan for one occurrence. Or in the case of that guy in WI who killed the hunters, maybe not plan at all.
A serial killer derives special joy from their ritual. Not that a mass murderer couldn't, but serial killers are heavily vested in ritual and habit.
As far as the 2000 decade having almost 60% of serial killers being black: first, I'd be interested to see when the study was done, if in the mid 2000's or after 2010, and I'd also like to know if it's the actual number of serial killers or if it's the percentage of of victims owed to serial killers of each race.
I'm not all that surprised that this decade has more serial killers that are black. The DC snipers were two black guys, and then of course there's Anthony Sowell in Cleveland. A few others this decade that escape my mind.
If someone wants to point out that serial killers require lots of attention to detail and planning (which is true) and then go to say that since most serial killers are white and use that as evidence that white people are predisposed to superior intelligence, I'd point out that by the same token white people seem to have a predisposition to possession, being deranged and devoting themselves to something wholly and totally evil. And one or both of the above may be true or not-- but it's nothing worth bragging about.
Anyways, Alaric, I would never say white people have a monopoly on serial killing. Go to any country that isn't predominantly white and you'll learn that. But I am saying that of serial killers in America, black people are a minority. That is verifiably true.