On the morning of July 8, 2014, 35-year-old Chad Aaron Gerber was found dead at his home on Atlanta Road in Laclede County, near Lebanon, Missouri, the victim of a gunshot wound to the head. The attack also fatally wounded his 15-year-old stepson, Riley Gerber, who later died in a Springfield hospital. Chad was a bricklayer and was training to become an Emergency Medical Technician.

Law enforcement focused on 65-year-old Matthew Mitchell Rumbaugh of Mountain Grove as a suspect, alleging a domestic-motive connection to Chad’s wife, Jennifer Gerber. Authorities said Rumbaugh had been frustrated over an alleged affair and that he was found and arrested sleeping at his son’s residence after the shootings. He was charged with two counts of first-degree murder, first-degree assault, and armed criminal action; the case was moved to Camden County and set for trial.

At trial in April 2019 prosecutors said Rumbaugh broke into the home with a Colt .38 revolver and shot both victims; prosecutors cited an earlier alleged admission that he went there to cause mayhem and remove Chad as an obstacle. Rumbaugh testified in his own defense, claiming Jennifer had invited him and that she shot Chad and Riley; Jennifer testified the opposite, saying Rumbaugh forced his way in and committed the killings. Who else was in the house and what exactly happened that night remain central questions.