The Last Quatrain of Emmett Till

I understood this piece to be Brooks interpretation of what this tragedy must have been like for Emmett's mother. People in class were saying that the poem seemed to be really simple compared to the previous poem, and I think that she did that on purpose. I think that because his mother was left with nothing but questions, the poem is not supposed to make complete sense. We can obviously understand that Emmett's mother was sad and upset in lines 7 and 8, "She kisses her killed boy./And she is sorry." But what does Brooks mean by, "She sits in a red room" or "through a red prairie"? I think she is using the word red to point to the fact that it was a brutal murder, with bloodshed that was not necessary. However, the meaning of those lines is not as clear and I think that Brooks did that to show that his mother had an unclear understanding as to why her sons murder was not facing justice.
~Jessica Mitchell