Who is Mrs. Merritt from Spoon River Anthology and what is their importance?

Mrs. Merritt says she was silent before the jury when the judge asked her if she had anything to say about her sentence of thirty years in prison, handed down to her for enticing her lover Elmer Karr to murder her husband Tom. She says she had warned Elmer to go far away, fearing she had maddened him with her body. Elmer did not heed her advice and Mrs. Merritt died in Joliet Prison.