Kentucky State Police are searching for motive as they investigate the fatal shooting of a district judge by a sheriff after the two had an argument inside the judge’s chambers, according to police.

District Judge Kevin Mullins, 54, was pronounced dead at the scene. Letcher County Sheriff Shawn M. Stines, 43, was arrested and charged with his murder.

Letcher County Sheriff Shawn M. Stines, 43, was taken into custody at the scene without incident, police said. He was charged with one count of first-degree murder.