Gunnery Sergeant Nieto enlisted in the Marine Corps in 2003 as a Military Police Officer.  After Graduating from Basic Military Police School he received orders to MCAS Iwakuni, Japan, for duties as a Military Police Officer. While assigned to MCAS Iwakuni he served as a Gate Sentry, Patrolman, Supervisor Patrolman, Dispatcher, and Desk Sergeant.  While assigned to MCAS Iwakuni, he was selected to attend the Basic Military Working Dog Handlers Course.  After graduation of the Basic Military Working Dog Handlers Course he returned to MCAS Iwakuni and assigned to the Military Working Dog Section for the remainder of his tour of duty.

In 2006, Gunnery Sergeant Nieto reported to MCAS Yuma, AZ for duty as a Military Working Dog Handler.  While assigned to MCAS Yuma Military Working Dog Section he served as a Patrol/Drug Detector Dog and Patrol/Explosive Detector Dog Handler. During his time in MCAS Yuma, he also deployed in support of Operation Iraqi Freedom as an Explosive Detection Dog Team.

In 2008, Gunnery Sergeant Nieto received orders to the newly formed Military Working Dog Platoon, Military Police Support Company, I Marine Headquarters Group, I Marine Expeditionary Force, Camp Pendleton, CA.  During this tour of duty he served as a Combat Tracker Dog Handler, Combat Tracking Dog Trainer, MWD Trainer, and Kennel Master.  During his time in Camp Pendleton, he deployed in support of Operation Enduring Freedom as a Combat Tracker Dog Handler and Trainer.

In 2013, Gunnery Sergeant Nieto reported to the Military Working Dog Team Deployment Course, Yuma Proving Grounds, AZ for duty as the Chief Instructor and Course Chief.

In 2016, Gunnery Sergeant Nieto reported to Marine Corps Recruit Depot San Diego, CA for duty as a Drill Instructor.

In 2019, Gunnery Sergeant Nieto reported to Marine Corps Base Quantico, VA for duty as a Military Officer.  During his time at Quantico he simultaneously served 
as the Law Enforcement Training Chief, Watch Commander, and Kennel Master.

In 2023, Gunnery Sergeant Nieto reported to his current position Military Working Dog Program Chief, Headquarters Marine Corps.

His personal awards are the Navy and Marine Corps Achievement Medal (4th Award) and the Combat Action Ribbon.