Supervision Team

Every law enforcement agency will tell you that the supervision core is the backbone of the department. Efficiency, effectiveness, and integrity of any organization relies in the hands of supervisors. They are the professionals who make sure the shift is running smoothly and assessing every aspect of the service being provided to the community. The Shafter Police Department has a great staff who we believe are among the best in the business. We’d like to use this forum to introduce them to you, their professional backgrounds, and their specialties.

Captain Randy Milligan

Captain Milligan was raised in a small town in Kern County. He became a Kern County Sheriff Reserve in 1999, and was hired as an extra help deputy sheriff shortly after. During the off season, as an extra help deputy sheriff, he worked as a Kern County Child Support Investigator and Housing Authority Investigator, assigned to investigations in the Shafter area. While working the Shafter area he realized how much Shafter reminded him of the town he was raised in with the presence of hometown and community values.

He was hired as a police officer with the City Of Shafter in June of 2003. He quickly volunteered for the special assignments of traffic officer and police fleet manager. As a fleet manager he worked diligently to bring the fleet to a professional and functioning level. He soon realized that emergency vehicles were becoming more complex and that a tremendous amount of work was required to get these units service ready. In 2004, he began to standardize the fleet by converting the fleet patrol units back to black and white patrol vehicles, as well as outfitting the fleet with consistent emergency equipment.

In 2004, he became the departments K-9 handler where he demonstrated how a highly dependable and devoted K-9 program should function. He worked with his partner Dak until Dak’s retirement in 2007.

He was selected as officer of the year in 2004 by his peers. He distinguished himself by receiving commendations from the Kern County and Denver Colorado District Attorney Prosecutors for his high quality of arrest and investigations. He has received numerous positive comments from his supervisory personnel regarding his high level of loyalty and dedication to the Shafter Police Department and other departmental personnel. He joined the long list of those officers who have distinguished themselves in the Shafter Police Department and the law enforcement profession.

In 2006, as he advanced in his career, he saw an opportunity to influence the future of the department and became a field training officer. In 2006, he was promoted to a senior patrol officer and in February of 2010 was again promoted to sergeant. In July of 2021 he was promoted to the rank of Lieutenant. In July of 2023 he was promoted to Captain.  

Captain Milligan serves as second-in-command to Chief Zimmermann. Captain Milligan supervises the lieutenants of the Administrative and Operations Divisions of the department.  

Sergeant Milligan

Lieutenant Joshua Stephens

Lieutenant Stephens was born and raised in Bakersfield. After graduating from high school he entered the United States Air Force as a Security Policeman. He was selected to become a Department of Defense K-9 handler in 2001. He was deployed to Iraq on two separate occasions. During those deployments he and his K-9 partner swept roadways and buildings for Improvised Explosive Devices. 

After being Honorably Discharged from the United States Air Force in 2006, he was hired as a police officer for the City of Valdosta in Georgia.  While working for the Valdosta Police Department he was selected as a member of the Valdosta Police Department Tactical Operations Unit. He worked closely with deputies from the Lowndes County Sheriff’s Office on numerous tactical operations.

In 2008 he was hired by the Shafter Police Department and attended the police academy at the Kern Regional Training Center. Since coming to the Shafter Police Department he has been assigned to several different positions. He was selected to work with the California Multi-Jurisdictional Methamphetamine Enforcement Team (CAL-MMET), which was a specialized assignment, focusing on narcotics investigations in the City of Shafter and areas in Kern County. 

In January 2013 Stephens was promoted to Senior Officer and in November of 2013 he was selected as the Shafter Police Department Detective. In 2014 then Senior Officer Stephens was awarded both his Intermediate and Advanced POST certificates. In 2015 he was named the Shafter Police Department Officer of the Year.    

Lieutenant Stephens has attended the 80 hour Basic Narcotics Investigation Course, the 80 hour Robert Pressley Core Course, a 40 hour sexual assault investigation course, Robert Pressley (40 hour) Officer Involved Shooting Investigation course, Kavanaugh and Associates 40 hour DUI Seminar, and many other training courses. 

In December 2017 he was promoted to Sergeant and returned to the Patrol Division where he led a patrol squad until January 2020.  In January 2020 he became the Shafter Police Department Administrative Sergeant and was promoted to Lieutenant in June of 2022.  

Lieutenant Stephens currently supervises the Dispatch Center, Property Room, and Records Division. 

Sergeant Stephens

Lieutenant Marvin Gomez

Lieutenant Marvin Gomez was raised in Bakersfield California and graduated high school in 1987. Upon graduation, Lieutenant Gomez joined the United States Marine Corps and served as an infantryman in 1991’s Operation Desert Storm/Sabre. After being Honorably Discharged from the Marine Corps in 1991, Lieutenant Gomez earned an Associate Degree in Business Administration from Bakersfield College.

Lieutenant Gomez began his career in public service in 1996 when he became employed as a Juvenile Group Counselor for the Kern County Probation Department. In 1999, Lieutenant Gomez accepted an appointment to the position of deputy sheriff for the Kern County Sheriff's Office. Lieutenant Gomez spent 20 years employed with the Kern County Sheriff's Office until his retirement in 2019 at the rank of sergeant.

In 2021, Lieutenant Gomez returned to law enforcement and joined the Shafter Police Department. In 2022, Lieutenant Gomez was promoted to patrol sergeant with the collateral duties of Gang Unit and Honor Guard Supervisor. In July of 2023, Lieutenant Gomez was promoted to his current position of Operations Lieutenant for the Shafter Police Department. Lieutenant Gomez has been afforded the opportunity to work numerous assignments throughout his career at both the Kern County Sheriff's Office and Shafter Police Department. The assignments include the following:

  • Field Training Officer
  • Recruit Training Officer for the Regional Training Center (P.O.S.T. Academy)
  • Crisis Negotiator Team Member
  • Special Weapons and Tactics operator
  • Gang Unit Supervisor
  • Narcotics Unit Supervisor
  • Patrol Unit and Area Supervisor
  • Honor Guard Supervisor 
  • Administrative Sergeant for Metro Patrol Operations
  • Gang and Narcotics Awareness Instructor for members of the community

As Operations Lieutenant, Lieutenant Gomez supervises the Patrol Section, Detective Section, Bike Patrol Unit, Traffic Unit, and Specialized Gang and Narcotics Investigations.


Sergeant Phil Yoshikawa

Sergeant Yoshikawa grew up in the agricultural area of Fresno County, where he went to school and then graduated from high school in 1988. He continued to live in the Fresno area, working and then attending the Fresno City College. He continued his education towards a Sociology degree, but chose to attend the Police Academy at the State Center Regional Training Facility in 1997. Upon graduating the police academy, he was hired as an entry level police officer for the City of Shafter Police Department. He saw the City of Shafter as a small farming community, where the values were similar to his upbringing and he felt he could be a benefit to the department and citizens of Shafter.

After a few short years of working as a patrol officer, he was given the opportunity to be assigned as the School Resource Officer (S.R.O.) and Drug Awareness & Resistance Education (D.A.R.E.) Officer for the Richland School District. In 2002, he was chosen as the Officer of the Year for the department. He later earned the rank of Senior Patrol Officer in 2004. During his time as an S.R.O., he worked closely with the schools in Shafter and the North Kern Superior Court with the area’s first Truancy Reduction Program. Six years later, he was reassigned from the role of the department’s S.R.O., back to patrol duties as a Field Training Officer and training all incoming officers for the next ten years. In 2010, he was again chosen as the Officer of the Year for the department. During this time, he also held the assignments as a Firearms Range Master and Fleet Coordinator.

In 2018, his role in the Shafter Police Department changed again, and this time he was assigned as a Detective. As the department’s detective, he continued his law enforcement training through the California P.O.S.T. and received an Auto Theft Investigator certification through the Robert Presley Institute of Criminal Investigation. His investigations of violent crimes, crimes against persons and property, has resulted in the conviction of the suspect(s) involved; taking them off the streets of Shafter and Kern County. The skills of collecting evidence during his investigations has given him one of the highest number of positive identifications of suspects in Kern County through the Automated Fingerprint Identification System.

In 2021, he was promoted to rank of Sergeant and was reassigned to Patrol Operations. Shortly after that, his role within the department changed as he was given the opportunity to become the Administrative Sergeant. During this assignment, Sergeant Yoshikawa was assigned to supervise the Dispatch Center, Fleet Services, and the department’s Recruitment Team.


Sergeant Moises Martinez 

Sergeant Moises Martinez was born and raised in the City of Los Angeles, California and moved to the Central Valley in 1990.  Sergeant Martinez attended and obtained a Criminal Justice Degree from California State University of Bakersfield and holds a CA. POST Advanced police certificate.   


Sergeant Martinez began his law enforcement career with the Shafter Police Department as a Reserve Police officer in April 2003, before accepting a full-time position as an officer in 2004.  Sergeant Martinez had the distinction of being selected as Shafter's first ever traffic enforcement officer, a position which he held for a period of about 2 years and issued a total of 2,520 traffic citations. As an officer, Sergeant Martinez was assigned as the School Resource Police Officer (SRO) for the Richland School District for approximately 2 years. During his time as an SRO, he was instrumental in developing the former Police Activities Program/Boxing Program. After serving with the City of Shafter Police Department, Sergeant Martinez went on to serve and work with a nearby law enforcement agency before returning back to the City of Shafter Police Department in 2019.   


After returning to the City of Shafter Police Department, Sergeant Martinez was promoted from Officer to Senior Police Officer. In July of 2022, Sergeant Martinez was assigned to work as a patrol sergeant supervising a patrol shift of four (4) officers. In July of 2023, Sergeant Martinez was promoted to his current rank of Sergeant.  Sergeant Martinez is married and the proud father of two. He has been the recipient of numerous Mothers Against Drunk Drivers (MADD) awards, including his 2020 Award for the arrest of 88 drunk drivers.  

Moises Martinez 2020

Sergeant Janet Fernandez 

Sergeant Janet Fernandez grew up in Delano, California and graduated from Cesar Chavez High School. After graduating high school, Sergeant Fernandez attended Bakersfield College and earned Associate Degrees in Administration of Justice, Criminal Justice, and Liberal Arts.

Sergeant Fernandez has prior experience working at the Kern County Sheriff's Office in both a civilian and law enforcement capacity. In 2016, Sergeant Fernandez joined the Shafter Police Department as an officer. In 2020, Sergeant Fernandez was promoted to the position of Senior Police Officer and worked as a senior police officer on patrol, which included the ancillary duties of Watch Commander and Field Training Officer. Sergeant Fernandez was assigned to the Detective Division for two years investigating felony crimes for the department. The criminal investigations included Attempted Murder, Robbery, Sexual Assault, and Fraud investigations.

During her time as a detective, Sergeant Fernandez collaborated with allied agencies to complete her investigations and assist them with their investigations. The agencies included the Federal Bureau of Investigation (FBI), Kern County Sheriff's Office, Delano Police Department, Tulare County Sheriff’s Office, and Tulare Police Department.

Sergeant Fernandez has completed training in the following law enforcement topics:

· Traffic Investigations

· Driving Under the Influence training

· Criminal Investigations

· Interview and Interrogation School

In 2018, Sergeant Fernandez was recognized for her efforts in combatting driving while under the influence by the Mothers Against Drunk Driving organization.

In July 2023, Sergeant Fernandez was promoted to Sergeant and assigned to patrol operations where she currently supervises a patrol squad consisting of a senior police officer and two patrol officers.

Fernandez PD

Sergeant Eric Diaz

Sergeant Eric Diaz was born and raised in Bakersfield, California. Sergeant Diaz started his law enforcement journey at the age of 15 by joining the Kern County Sheriff’s Office Explorer Program. Sergeant Diaz has attended California State University, Bakersfield is currently still working on obtaining a Bachelor’s Degree in Business Administration with a concentration in Human Resources.

Sergeant Diaz attended the POST Basic Academy presented by the Kern County Regional Training Center as a student. Sergeant Diaz accepted a position with the Shafter Police Department and was sworn in as a Police Officer on April 27, 2015. Sergeant Diaz has participated in every special assignment and ancillary duty offered by the department. As a patrol officer, the special duties Sergeant Diaz worked were: traffic enforcement, Gang Unit, Community Resource Officer, served as an informal Field Training Officer, and watch commander. As a patrol officer, Sergeant Diaz’ efforts led him to obtain multiple commendations and he received two (2) MADD awards due to his efforts in removing drunk drivers from the roadways.

In 2019, Sergeant Diaz was assigned to the Kern County High Intensity Drug Trafficking Area (KC-HIDTA). While in KC-HIDTA Task Force Sergeant Diaz was involved in hundreds of large illegal drug seizures. Sergeant Diaz has worked alongside numerous local and Federal agencies including: United Stated Attorney General, Federal Bureau of Investigation, Homeland Security Investigation, Drug Enforcement Administration, Airforce, and the Army National Guard. While in the KC-HIDTA Taskforce, Sergeant Diaz also assisted local and federal agencies in the apprehension of suspects associated with violent crimes such as murder, attempted murder, robbery, and sexual assault. Sergeant Diaz has testified in court as a narcotics sales expert.

Sergeant Diaz returned patrol and promoted to Senior Police Officer in August of 2022. As Senior Officer, Sergeant Diaz assumed the role of School Resource Officer (SRO) at the Richland School District. As SRO, Sergeant Diaz was responsible for Richland Junior High, Redwood Elementary, Golden Oak Elementary, and Sequoia Elementary.

Sergeant Diaz promoted to Patrol Sergeant on September 16, 2023 and currently supervises a patrol shift consisting of four (4) officers.


Sergeant James York

Sergeant James York was born in Illinois and moved to Bakersfield in 1983. He attended High school and College in Bakersfield before moving to Sonoma County. Sergeant York completed the basic Police academy in 1997 and holds a CA POST Intermediate police Certificate by the California Commission on Peace Officer Standards and Training.

Sergeant York began his career as a Law Enforcement Officer with the Marin County Sheriff’s Office in 1999, where he worked in various assignment including custody, courts, and patrol. He also held several specialty assignments including, Field training Officer, Human Trafficking Unit, Gang Unit, and SRT. Sergeant York was a Field Training Officer for 18 years and a Defensive Tactic instructor for 12 years. Sergeant York retired from the Marin County Sheriff’s Office in 2020.

Sergeant York started working for the Shafter Police Department as a patrol Officer in 2020 and was selected as a Range Master in October of 2020. Sergeant York was promoted to Senior Patrol Officer in August of 2021 and promoted to his current rank of Sergeant in September of 2023.

Sergeant York has received over a 1000 hours of advance officer training in various fields including specialty training in Firearms, Crowd / Riot control, Defensive tactics, and Special Weapons and Tactics. Sergeant York has received two Life Saving Awards, the Medal of Merit for Heroism, and the Medal of Valor from the California Chiefs Association. Sergeant York met his wife in Shafter and they have been married for 32 years. They are the proud parents of four adult children.

Sergeant York is currently assigned as a patrol sergeant supervising four (4) patrol officers.

James York II

Animal Control Manager Nick Riddick

Animal Control Manager Nick Riddick was born and raised in Fresno, California. He attended the University of California, Riverside leaving for a supervisor position at a Fortune 500 Company.

Life would lead him back to the beautiful San Joaquin Valley, however, and to the City of Shafter which he now calls home. Nick has been a resident in Kern County for nine years, where he found his calling in the Animal Control field.

In November of 2009, he accepted a position as an Animal Control Officer for the County of Kern. He was selected as the Lead Officer in the newly revamped Public Education and Enforcement Team Program, or PEET.  This program consisted of public outreach to promote the importance of licensing and vaccinating pets as well as responsible pet ownership.

With a successful tenure as the “PEET” Officer, Nick ventured into field services which entailed responding to a variety of animal related issues. It was not until he began responding to reports of Animal Cruelty and seeing firsthand the kinds of terror that can be inflicted upon animals that he realized he had a golden opportunity to effect change, hold people accountable for their actions, and save lives. He carries this creed to whatever situation life presents and is steadfast in upholding these values for the citizens of this community.

In 2013, Nick accepted the position of Animal Control Manager for the City of Shafter, bringing with him the experience and understanding of community involvement and participation. This has resulted in an increase adoption levels and rescue live release rates of animals, while steadily maintaining increased animal intake numbers and calls for service.

Nick has a team of professionals and volunteers who are vigilant in impounding stray and marauding animals, but also dedicated to work toward lowering the annual euthanasia rate. This multi-pronged approach is accomplished partially with increased live release rates, carefully vetted rescue partners, and a thriving volunteer program.

In 2015, Officer Riddick was awarded the Officer of Year and continues to strive for the dedication to service the citizens of our community deserve.

ACM Riddick