Please do better research. This was a very easy find on the race of the person executed. The Times is leaning the article toward their viewpoint and is hardly unbiased.
White criminals are executed more than black criminals. The victim comparison would included black on black crimes with gang on gang included. The shooter is less likely to get the death penalty for shooting another gang member shooting at him.
62% of white victims are violated by white criminals. 70% of black victims are violated by black criminals. According to your study the criminals violating black victims are not getting executed at a high enough rate however, 70% are black criminals. If those that violated black victims are facing a higher execution rate there would be people complaining black criminals are getting executed much more.
Executions by Race and Race of Victim | Death Penalty Information Center
https://www.bjs.gov/content/pub/pdf/cv18.pdf