This is an old myth that is dying a hard death.
Serial Killers 1980-2000 Census Race White 58.94 74.40 Black 32.12 11.95 Hispanic 6.70 9.55 Asian 1.12 2.81
From here. Other figures have been shown before on my site and other sites.
I am not sure how to do statistics, but just guessing here, it looks like Blacks are 3.4 times more likely to be serial killers than Whites are. Hispanics and Asians are less likely to be serial killers than Whites are. Asians are the least likely to be serial killers, then Hispanics, then Whites, and last Blacks.
Serial Killer Odds Ratio Race Black 2.69 White .79 Hispanic .70 Asian .40
Blacks are about 3.5 times more likely than Whites or Hispanics to be serial killers, and they are about 6.5 times more likely than Asians to be one.