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

Tom Merritt tells the reader he first suspected his wife was cheating on him when she began acted strangely calm and absent-minded. Merritt knew for certain, he tells us, when one day he heard the door shut and saw Elmer Karr slipping out the back. Merritt says he intended to kill Karr on sight, but he ended up coming upon Karr unexpectedly, and Karr shot him.