Why does race matter?

White people kill other white people also. But when a black person kills someone white, people get racist why is this? White man john Gardner killed chelsea king, Jerry Buck inman killed Tiffany souers, Michael King killed Denise Amber Lee, James Biela killed Brianna Denison, David Sullivan killed Anna Svidersky, Shaun Earl Arender raped and hanged a 6 year old girl from a tree. White people kill other whites also, so why do whites get mad when a black kills a white, your more likely to be killed by your own race.