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Thurston County, Washington

The content on the Thurston County website is currently provided in English. We are providing the “Translation” for approximately 10 languages. The goal of the translation is to provide visitors with limited English proficiency to access information on the website in other languages. The translations do not translate all types of documents, and it may not give you an exact translation all the time. The translations are made through an automated process, which may not result in accurate or precise translations, particularly of technical and legal terminology.


The Sheriff's Office is organized around Bureaus - Corrections, Field Operations, Financial Services, and Support Services.

Select the Sheriff Organization Chart and the various leaders below to find out more about each bureau and the leaders within the Sheriff's Office.

Sheriff's Department Organization Chart


Sheriff Derek Sanders served the citizens of Thurston County as a Deputy for six years before securing an election win to become Thurston County’s 24th Sheriff. Sheriff Sanders ran on a platform of improving employee morale, greater office transparency, and introducing technology-based solutions for problems facing our community. During his tenure as a Deputy, he engaged in community service events, was awarded the Medal of Valor and two Lifesaving awards, and was routinely commended by both victim’s and those suspected of committing crimes for his relentless effort to solve crime while respecting the rights of both parties.

Sheriff Sanders prides himself on being known regionally as a “crime magnet”, regularly finding himself in the middle of active police work both as a Deputy and the Sheriff. Pulling from childhood experiences, Sheriff Sanders maintains high expectations of both state and county improvement in the areas of domestic violence, homelessness, and poverty.

Sheriff Sanders enjoys working on cars, boating, and engaging with community members.

Photo of Undersheriff Dave Pearsall

Undersheriff Dave Pearsall served the citizens of Thurston County for 36 years in law enforcement before retiring. Undersheriff Pearsall was raised in Thurston County and started his young career with TCSO as an explorer/cadet before becoming a Reserve Deputy. In 1985, Undersheriff Pearsall was hired on as a full time Deputy Sheriff and worked his way up the ranks for more than three decades. During his tenure, Undersheriff Pearsall has served as a Patrol Deputy, Forestry Deputy, Marine Services Deputy, Off Road Vehicle Deputy, Narcotics Detective, and SWAT Team Incident Commander before being appointed as a Chief through two separate administrations.  Undersheriff Pearsall has managed nearly every unit within the Sheriff's Office, to include Patrol Division, K9, Marine Services, Dive/ Rescue, Investigations, Homicide Investigations, Civil Division, Records Division, and Evidence Division. He was instrumental in bringing in new technology to TCSO over the last decade and has experience in filling in as Undersheriff during his career. Undersheriff Pearsall is a graduate of Command College, Executive Leadership Training, and is an FBI National Academy graduate. He serves as an elected Fire Commissioner for District 13 and is the president of the Thurston County Chaplains Association for Public Safety. 

Photo of Executive Aide Kari Knies


Executive Aide Kari Knies served the citizens of Thurston County for 7 years before resigning to take a job with the State of WA a few months ago. Kari worked as an Executive Assistant for The Valley Athletic Club for 7 years, assisting the owner with the successful operation of the fitness facility in addition to helping set up new venture businesses. Kari was hired on with TCSO in 2015 and served as a Legal Assistant in Records, Warrants, Civil, and Public Disclosure Request Unit (PDR). Kari has served on a number of committees during her time with TCSO pertaining to GEO Data Sheriff Focus Group, County Safety Committee, TCSO Phone App, PDR Unit Training Manual, RMS Replacement Committee, TCDSA Executive Board Secretary and Support Vice President, and was an integral part in TCSO’s web page revamp. Kari has served as a temporary supervisor within support services, and has also filled in as the TCSO Executive Aide position on numerous occasions.  


Photo of Chief of Operations Ruben Mancillas

Chief Ruben Mancillas has served the citizens of Thurston County for 22 years. Chief Mancillas started his law enforcement career as a reserve with Molalla Police Department in Oregon where he grew up. After graduating high school, Chief Mancillas enlisted in the U.S. Army where he selflessly served over 20 years as an Explosives Ordinance Disposal Specialist (EOD). Chief Mancillas retired from the National Guard after serving as the First Sergeant of his EOD Company. Chief Mancillas deployed numerous times throughout his military career. Chief Mancillas completed the Basic, Advanced and Senior Non-Commissioned Officer Courses; he received the Basic, Senior, and Master Explosive Ordnance Disposal, and Team Leader Certification Awards. During his tenure with TCSO, Chief Mancillas has held the rank of Narcotics Detective, Patrol Sergeant, Administrative Sergeant, and Patrol Lieutenant. Chief Mancillas has served as an Animal Cruelty Investigator, Field Training Officer, Air Operations Deputy, Firearms Instructor, Less Lethal Instructor, Firearms Program Manager, Radar / Lidar Instructor, Marine Service Unit Operator, Marine Service Unit Manager, Clandestine Meth Lab Operator, SWAT Team Operator/Leader/Commander. Chief Mancillas has attended training for First Level Supervision, Middle Management, Command College, National Tactical Officer Team Commander, and FBI LEEDA Supervisor/Command/Executive Courses. Chief Mancillas received the Medal of Courage and Lifesaving Award. 

Chief Carla Carter has served the citizens of Thurston County for 21 years. Chief Carter has held many roles within her time at TCSO, to include: Field Training Officer, founding member of the Animal Cruelty Team, Bike Patrol, Explorer Advisor, Sergeant, Detective Sergeant, Public Information Officer, Operations Lieutenant, Commander of the Crisis Negotiation Team, CERT team Commander, served on Honor Guard and Peer Support Team Leader. Chief Carter has also managed several departments to include our civil division, firearms, public disclosure, evidence, and warrants. She is a strong advocate in her community and has served as president on the Board of Directors of Safeplace, and Board of Directors of the Dispute Resolution Center. Chief Carter has sponsored two (2) littles with Big Brothers Big Sisters, is a Camp Hope Mentor, has participated in the Special Olympics Torch Run, Adopt a Family, created a 501C3 for our K9 units, and regularly attends charity functions.  Chief Carter has served on victim support task forces for human trafficking, domestic violence, sexual assault, and child victims. She has been recognized as a Women of Excellence by Soroptimists, a Champion for Kids, and has received the Sheriff's Award of Excellence and the Domestic Violence Amethyst Awards. Chief Carter received her BA from Western Washington University and Oregon State University. She has graduated Command College, the Women's Leadership Institute, FBI LEEDA Trilogy, 21st Century Leadership in Policing, and Guardian Officer Leadership Development. 

Chief Trevor Davis has served the citizens of Thurston County for 15 years. After graduating high school in Miami, Chief Davis enlisted in the U.S. Army. Chief Davis spent time in Germany, Ft. Polk, and Ft. Lewis before being deployed to Haiti for an election peace-tour. Chief Davis returned to Washington in 1996 with his wife and decided to call Washington home. Chief Davis started his Corrections career at Green Hill as a supervisor while remaining enlisted in the National Guard. In 2004, Chief Davis answered the nations call and was deployed to Iraq for Operation Iraqi Freedom where he spent 18 months overseas. Upon return, Chief Davis was hired by TCSO as a Corrections Deputy. Chief Davis has served as an instructor for Defensive Tactics, Pepperball, and Taser. Chief Davis is very proud of his service with TCSO’s Honor Guard, a capacity he still serves in to this day as an Assistant Commander. Chief Davis believes there is nothing more honorable than honoring those who paid the ultimate sacrifice. Chief Davis has volunteered as a  coach for his son’s Youth Football League, and he is very proud of his two children: a daughter who served 5 years in the US Navy on the USS Reagan, and a son who played Division 1 football at Eastern before enlisting in the National Guard to become a pilot. Chief Davis has served as a Deputy, Sergeant, and Lieutenant during his time with TCSO.

 Chief Heidi Thomsen Thomsen has served the citizens of Thurston County for 8 years. Chief Thomsen currently serves in the role of Financial Operations & will be retained from the previous administration. Chief Thomsen started her career with the State of WA holding clerical positions with The Department of Natural Resources in 1995 before working as a Budget Management Analyst. Chief Thomsen then served the WA State Patrol as a Budget Management Analyst, managing 215.75 FTE’s and $48.3 million. Chief Thomsen became the Senior Budget Management Analyst for WA State Department of Social and Health Services for the Children’s Administration Budget (2,488.6 FTE’s, $991 million). Chief Thomsen returned to WA State Patrol as the Budget Manager in 2007, overseeing the entire WSP agency budget containing 2,422 FTE’s and $512 million. In 2014, Heidi joined TCSO as a Chief where she currently serves to this day. Chief Thomsen is responsible for organizing and controlling all financial aspects of the Sheriff’s Office. Chief Thomsen is involved in all things finance at TCSO, including long term financial planning, legal compliance, and analysis and interpretation on revenue and expenditure data trends. Chief Thomsen is earning her master’s degree in Public Affairs from The University of Missouri – Columbia, is a Certified Fraud Examiner, & serves on the Thurston County Fair Board & Thurston County K9 Unit Foundation.