The assailant was arrested after the incident and is being held at the Gigiri police station for questioning.
He shot his Administration Police colleague three times in the chest killing him instantly.
Senior police officers who visited the scene said there were signs of a long scuffle between the two before the shooting happened.
Muturi and his family were not present at the time of the incident. They were in Mombasa.
It's not clear what caused the scuffle. Gigiri OCPD Vitalis Otieno said they would interrogate the assailant officer for more details on the motive of the shooting.