The Big Gundown (1967)

Jonathan Corbett is a gunman so brave to have eliminated all the bandits of Texas. For this he is proposed for the candidacy to the Senate of the United States. In exchange he has only to support the construction of one railway line. Only after he accepts does he come to know that the Mexican Cuchillo has raped and killed a 12 year old girl. Corbett leaves on a long manhunt during which he gets to know his adversary better and discovers a variation on the crime for which the accused Cuchillo may not be as guilty as he first thought.