... people quote phantom studies from 1990 ... 22 frickin' years ago ... but no actual data is shown.

Then, the DPIC study doesn't show who killed whom ... it just shows distribution of perps and victims. Totally useless. A true study would show the following homicide data in a single table:

Total felons by race
Total felons receiving death penalty by race
Total felons executed by race
Percent of felons receiving death penalty by race
Percent of felons executed by race
Race distribution of victims by race of felons
Race distribution of victims by race of felons receiving death penalty
Race distribution of victims by race of felons executed

Then, it would be handy to see the same data by state.
Percent of felons

Otherwise, the studies are just useless bullshit.