Brothers (Western Frontier Justice War) by Jesse Storm

Jameson knows his brother, Holden, is no killer. He would have never gunned down an innocent man. The town’s residents are eager to hang Holden which is why Jameson urges the sheriff to give him some time to bring in the real perpetrator. The sheriff is reluctant, but he gives Jameson a week to find the killer, otherwise his brother will be hanged.