Lee Mosier and Robert Arner were traveling with Hugh Benton Lawler on a trip from Anthony, in Indian Territory, to Kansas, on October 27, 1886. Without warning or provocation, Mosier, who was 20-years old, shot and killed Lawler. He then drove off with Lawler’s wagon while Arner escaped. The killing occurred within Indian Territory.
A search party found and arrested Mosier on October 31. He was held for trial is federal court in Wichita. When arrested and at trial, Mosier claimed he was first introduced to the plan to kill Lawler by Arner. Once he agreed, he and Arner were hired by Lawler’s wife, who was reported to be much younger and estranged, to kill her husband and were paid $2,000.
In the state’s version of events, Mosier’s motive was robbery and Arner, who was not involved, was spared in return for his promise of silence. Allowed to leave after the shooting, Arner quickly reported what had happened.
Prior to Mosier’s trial, Mrs. Lawler was arrested and tried for her alleged role. She was acquitted.
At trial in federal court in September 1887, the State’s version of events prevailed. No evidence was presented to corroborate Mosier’s story. Mrs. Lawler and Arner testified against Mosier.

Mosier was found guilty on September 15, 1887, and sentenced to death. Lee Mosier was hanged on November 15, 1887.