From Halopedia, the Halo wiki
Corporal Robert Grove (service number 081225-78081-RG) was a human enlisted in the United Nations Space Command's Marine Corps. Prior to enlisting with the Marine Corps, Grove was an officer of the Elysium City Law Enforcement on Eridanus II. As a law enforcement officer, he used the WST DTM/Law Enforcement. During the Human-Covenant War, Grove was interviewed by Doctor Robert McLees for comments about the M90 Close Assault Weapon System, as part of Doctor McLees' report on technology used during the war. Though satisfied with the weapon's adjustable stock, Grove voiced his fondness for the DTM/LE.