Meet our team at Summit Malibu in beautiful Malibu, California where we have experience in treating drug and alcohol addictions, with great success.  We’re with you every step in the process from before and after treatment. Get to know our team below.


William Oswald, Chief Executive Officer, and Founder

Summit Malibu was founded by William Oswald, who has over 40 years of experience in the field of substance use, addiction treatment, and mental health recovery.

As a hands-on owner in recovery himself, William has handcrafted the Summit Malibu treatment program by drawing upon his extensive experience with proven methods for long-term success. Read More

nicholas mathews

Nicholas Mathews, CFO

Nicholas Mathews is a passionate and committed treatment provider in every aspect of his professional life. A resident of Southern California by way of Oregon, He started his career in behavioral health as a result of his own profound experiences with personal recovery and knew his passion lied with giving back to a population of his peers. Mr. Mathews is a serial healthcare entrepreneur with every venture he undertakes dedicated to helping individuals struggling with addiction and mental health disorders.

Medical Team

Harsh Brar

Harsh Brar, N.P.

Harsh Brar is a Board Certified Family Nurse Practitioner. Harsh received his Bachelor of Science in Nursing from West Coast University in Los Angeles and his Master of Science in Nursing from Samuel Merritt University in Oakland. Harsh has a special interest in a variety of different medicines including addiction, concierge, and pain.

Erika Kamish, P.A.

Erika Kamish, P.A.

Erika Kamish is a nationally board-certified Physician Assistant and is licensed by the California Physician Assistant Committee. She received her bachelor’s degree at Yeshiva University in NYC before attending Western University of Health Sciences’ physician assistant program. Erika has a special interest in primary care, addiction and aesthetic medicine.

William Stanley, M.D.

Dr. William D. Stanley, M.D., received his Doctorate of Medicine degree from UMDNJ – Robert Wood Johnson Medical School in Piscataway, NJ.

Dr. Stanley completed his Boards for ASAM (American Society of Addiction Medicine) in 2000, and later for ABAM (American Board of Addiction Medicine) in 2010. Read More

Shahla Modir, M.D.

Dr. Shahla Modir, M.D., has over 20 years of experience in addiction, psychiatry, and integrative medicine.

Dr. Modir is dual board-certified in Addiction and Psychiatry, serving as a diplomate of the American Board of Psychiatry and Neurology and its Addiction Psychiatry certification. Read More

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Kevin Simonson, Psychiatrist

Dr. Kevin is a psychiatrist with an integrative approach to mental health treatment. He completed his BS in Molecular Biology with minors in Chemistry and Psychology at Humboldt State University. He received his medical degree from UC Irvine and completed residency at UC Riverside and the Long Beach VA, where he worked in substance treatment and suboxone clinics.

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Anita Hansen, D.C.

Dr. Anita Hansen is a Doctor of Chiropractic. She received her Undergraduate Degree from UCLA in 1991 and her Doctorate from Cleveland Chiropractic College in Los Angeles in 1996. She has worked specifically with patients at rehabilitative facilities for the past eight years. Dr. Hansen treats her patients on-site, focusing her expertise on eliminating the patient’s pain and enabling them to be stronger physically which, in turn, increases their immune system. Specializing in understanding the physical issues most common and prevalent with rehabilitative patients, Dr. Hansen successfully pinpoints how to best resolve the patient’s area of complaint. She is passionate about having this ability and skill which is conveyed to her patients.


Kristin Robert, Executive Director

Hailing from a background in business administration and customer service, Kristin Robert joined the team at Summit Malibu in January 2014.

As Executive Director, she oversees the clinical and support staff, as well as all aspects of our dual diagnosis addiction treatment program. Read More

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Kam Walton, Director of Operations

Kam Walton brings her background in management to our team at Summit Malibu. Prior to joining Summit in 2022, she was a communications major at UCSD and SDSU.

Kam has worked in the field of addiction treatment for over six years and takes a personal interest in all Summit employees as well as clients. Read More

Clinical Team


Kelly Sweeney, Case Manager/Aftercare Coordinator

Kelly Sweeney has worked in all aspects of the addiction and mental health treatment field for more than 16 years and currently serves as Case Manager and Aftercare Coordinator for Summit Malibu.

She has had the exclusive opportunity of working alongside some of world’s very best clinicians, treatment centers, and doctors. Read More

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Amaris Baker, LMFT, Clinical Director

Amaris Baker is a graduate from the University of Nebraska-Lincoln where she earned her Bachelor of Arts (BA) in Psychology and minored in Sociology.

She obtained her master’s degree (MA) in Counseling: Marriage and Family Therapy at California State University-Long Beach. Read More

Beth Farar, LMFT, Independently Affiliated Clinician

Beth Farar is a California State Licensed Marriage, Family and Child Psychotherapist (LMFT) who has been treating people for more than 22 years.

She specializes in working with individuals, couples, children, adolescents, and family therapy and is trained in Rapid Resolution Therapy. Read More

Gabriel Logan-Braun, Holistic Practitioner

Gabriel Logan-Braun has shared his knowledge and touched the lives of both our team and residents since arriving at Summit Malibu several years ago in 2018.

After going through a dark episode of depression in his late teens, he was led to his first yoga class at the age of 17, where he began his journey of healing and transformation. Read More

Natalie Riggs, Equine-Assisted & Yoga Therapist

Natalie Riggs provides a dual role as both an experienced Equine-Assisted Therapist and Yoga Therapist for our residents at Summit Malibu.

She facilitates therapeutic group and private sessions for our clients by navigating a myriad of life challenges including post-traumatic stress, anxiety, depression, and addiction. Read More

Terry O’Rourke, CADC, Group Facilitator

After a successful career in film & tv production, Terry felt it was time to give back. He has been blessed in his life with many gifts and felt it was time to be of service to others. Terry’s mission statement is “I co-create a world of connection and discovery through supporting, facilitating, and loving myself and others.” He graduated from the UCLA Extension Addiction Studies Program In 2018. Terry then became a Certified Alcohol and Drug Counselor. He is also a certified SMART Recovery Facilitator.

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Jonathan Kim, CADC, Group Facilitator

Jonathan is a highly skilled and compassionate certified drug and alcohol counselor with extensive experience in helping individuals overcome substance abuse and addiction. With a genuine passion for making a positive impact on people’s lives, Jonathan has dedicated his career to guiding individuals through the challenges of addiction and providing them with the tools they need to achieve lasting recovery. Read More

Support Staff

Paul Croonquist, Admissions Coordinator

Paul Croonquist, Admissions Coordinator

Paul Croonquist joined the Summit Malibu team in 2023. After a 25 year career as an entrepreneur and business owner, Paul felt driven to work in the field of addiction as helping others is his passion. When Paul joined us in 2023, he had accumulated 36 years of sobriety. The combination of years of service work, experience as a business owner and personal knowledge of addiction makes Paul an asset to Summit. Read More

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Brooke Schwengel, Supervising RN

Brooke is the Supervising Registered Nurse for Summit Malibu Treatment Center. She holds a Bachelor of Science in Nursing degree. Prior to working in mental health and addiction treatment, Brooke managed several clinics for covid testing. Read More

Joanna Medina

Joanna Medina, Medication Room Supervisor

Joanna Medina earned her Bachelor’s Degree from California Lutheran University and she began working in field of addiction treatment immediately after she graduated.

Joanna’s personal experience with addiction provided the motivation for her to work in treatment, where she can provide support, compassion, and hope to others. Read More

Cortney Critser

Cortney Critser, Medical Assistant

Cortney was born and raised in Thousand Oaks, California. She is a great addition to the team as she is a certified medical assistant. When Cortney isn’t at Summit, she works as a professional hairstylist and loves to travel. She struggled with addiction herself and has been clean and sober since early 2017.

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Donald Peake, Lead Clinician Assistant

Don Peake was born and raised in Seattle, Washington, and moved to the Los Angeles area in the early ’70s with his wife Pam.

He draws from his own personal experience in recovery when sharing with clients and offering compassion and encouragement during their time in treatment and beyond. Read More

Scott Naslund, Lead Clinician Assistant

Scott is a graduate of UCLA and has been working at Summit Malibu since its inception. His experience in recovery has been both challenging and rewarding. The challenge has lied in helping people through the throes of addiction by being supportive. The reward from witnessing people heal through Summit’s therapeutic process and rekindle their fire for life. His passion for learning has helped him realize the importance of helping people and the value of sobriety.

Jesse Alldredge

Jesse Alldredge, Clinician Assistant

Jesse Alldredge is a wonderful addition to the Summit team and has worked in the field of recovery for two years. He is passionate about working with others while using his own personal experience to help guide them.

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Rosalia Sandoval, Facility Manager

Rosalia Sandoval has been a member of the Summit Malibu Team from day 1 and excels as our Facility Manager.

She enjoys interacting with our clients and staff, and is present every day, welcoming Summit Malibu with a fresh breakfast and a warm smile. Read More

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Mark Rabbene, Executive Chef

Chef Mark Rabbene attended the Culinary Institute of America and began his career in the food industry in 1983. He has held many titles such as Apprentice at Four Seasons Restaurant, Corporate Chef for AT&T, and has been the owner of two restaurants back in his hometown of New York. Read More