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Senior Team

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Pat Ryan, Interim Chief Executive Officer

     Pat has extensive leadership experience in acute care hospital operations, physician partnerships, clinical service lines, joint venture management, and the continuum of care, including skilled nursing, home health, acute rehabilitation, and behavioral health.
     Pat most recently served as Chief Executive Officer of Sutter Health’s Eden Medical Center, a 130-bed neuro-interventional and level 2 trauma center in Castro Valley, CA. Prior to this, Pat served as Chief Operating Officer and Interim CEO for O’Connor Hospital in San Jose, CA, guiding the hospital through Verity Health System’s Chapter 11 bankruptcy and helping to successfully transition ownership to the County of Santa Clara.
     Previously, Pat held senior positions for Sutter Health’s Mills‐Peninsula Medical Center in Burlingame, CA, providing strategic and operational leadership for ambulatory services and service lines, including oncology, joint replacement, behavioral health (psych emergency, inpatient adolescent & adult, and intensive outpatient programs), and cardio-vascular, including implementing a TAVR program. She also held senior leadership positions at Princeton Healthcare System in New Jersey and Main Line Health System in Pennsylvania. Pat managed acute care hospital functions and the post-acute continuum for both organizations, including home care, hospice, skilled nursing, subacute, acute rehabilitation, adult day care, and long-term care.
     Pat holds a Bachelor of Social Work from Juniata College in Pennsylvania and a Master of Health Administration from The Pennsylvania State University.

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Diahann Barrera, Chief Financial Officer

     Diahann brings over 30 years of experience and expertise in finance, operations management, and administration within both for-profit and non-profit organizations, significantly contributing to the healthcare industry. Her journey began in dental healthcare before expanding into the medical field in 1994, underscoring her versatility and commitment to healthcare advancement. After earning her Master of Business Administration, Diahann ascended to the role of Vice President of Finance and Operations for a Community Health Center in 2002, where she demonstrated her proficiency in managing complex budgets up to $120M.
     In March 2024, Diahann took a significant step by joining John C Fremont, bringing her wealth of knowledge and strategic vision to the institution. Her engagement doesn't stop at professional achievements; Diahann is deeply involved in her community, reflecting a leadership style that is both impactful and grounded in a genuine desire to contribute to societal well-being.

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Craig Burchfiel, Chief Information Officer

     Craig Burchfiel's career spans over four decades, starting in Palm Springs where he led a team of 40 in building and automating sand plants from 1980 to 1989. He then pivoted to finance, owning a mortgage company until 1997, before shifting to IT. Starting in 1998, Craig worked as a virtualization consultant for school labs, significantly reducing costs by optimizing resources. While consulting with local schools and raising his family, Craig obtained his AA degree in Network Engineering and Cyber Security and graduated with honors.
     Joining JCF in 2012, Craig established and has led the IT department, transforming it into a vital asset for our district. His leadership has not only propelled technological advancements but also fostered a strong community connection. Craig is truly humbled and blessed to contribute to our district's ongoing success and development.

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Thomas Wilkinson, Chief Nursing Officer

     Thomas brings a rich and diverse background to the JCF leadership team. Starting in the propane industry in Vermont, Tom transitioned to healthcare, demonstrating exceptional dedication and skill. As a valedictorian of his nursing class, he has extensive experience in emergency and critical care nursing, highlighted by his work in Emergency Rooms and as a Critical Care Transport RN. After moving to California in 2013, Tom's leadership abilities flourished, leading to roles such as RN house supervisor and ER charge nurse, culminating in his tenure as Chief Nursing Officer
     With board certifications in Emergency Nursing (CEN) and Critical Care Nursing (CCRN), and a Master of Nursing (MSN) from Capella University in Leadership/Administration and Education, Tom is not only a committed healthcare professional but also a passionate musician. He is eager to leverage his expertise and enthusiasm to drive positive changes and enhance community services at JCF.

Photo of Colleen Choi

Colleen Choi, Chief Operating Officer

     Colleen has had the pleasure of growing up in various lovely locations in California and Nevada, including Loma Linda, Lodi, Las Vegas, Fresno, Reno, Riverside, Bakersfield, and now Mariposa. With deep roots in California, she has a strong connection to the state.
     Coming from a healthcare family, she was immersed in the field early on. Her mother is a Pathologist, her father was a Pharmacist and Lawyer, her aunts are Registered Nurses, and her uncle is a Pediatrician. Although she initially aimed to be a Psychiatrist, she discovered her passion for accounting during her freshman year in college.
     At La Sierra University, where she met her husband, she graduated Summa Cum Laude with a BS in Accounting in 2011. They married the same year and welcomed their first child in February 2012. While raising their child, she passed her CPA exams and earned her license by 2016, starting her career at Daniells, Philips, Vaughan & Bock in Bakersfield. Her experience spanned various sectors, including healthcare, agriculture, oil & gas, and non-profits.
     In 2017, her family moved to Mariposa, where she founded Mountain Family Tax Preparation in 2018, offering local CPA services. Her mission has always been to empower clients with financial knowledge.
     By 2022, she returned to an office environment as the Controller for the healthcare district. She helped complete not one, but three financial audits in record time of six months, on top of improving financial reporting processes. Promoted to Director of Finance in 2023, she helped prepare the FY24 budget and secured a $9.35 million HCAI Distressed Hospital Loan. As COO, Colleen’s goal is to enhance the health of Mariposa County residents while ensuring fiscal stability.
     Currently, she and her husband live on a 10-acre property in Mariposa with their three children, one cat, and two sulcata tortoises.

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