Meet Our Dedicated Team
Cornerstone prides itself on being a family-run, community-focused business. Understanding the importance of community means we truly understand the importance of quality staff, for these people form the heart, the cornerstone of our community. As such, we aim to offer outstanding employee benefits to our staff, as we know we get back what we put in.
Cornerstone is proud to boast a team of the most highly skilled experts in the Substance Use and addictions field. Our staff are all fully trained in treating chemical dependency and related addictions. We also employ many people with experience of substance use disorders or addiction themselves, as we understand that those who have been through the recovery process are well equipped to help another recovering addict get to where they are. We are exceptionally proud of our 90 employees and affiliates.
Over the years we have attracted some of the most senior members of Orange County’s medical and psychological team. Many wanting to work for us because of our exceptional working conditions, camaraderie and sense of community.
Michael Stone, MD, FAAFP, ABAM, FASAMFounder and Chief Medical Officer
Jiseung David Yoon, MD, MPHPhysician
Jeanette Ponce, MDPhysician
Dr. Ponce is Board-certified in Family Practice with a solid knowledge base and experience with addiction issues and medicine. She has extensive experience providing integrated primary care for patients with mental health and alcohol and drug-related issues serving as a family practice physician, internal medicine hospitalist, internist, and health educator during her career.
Dr. Ponce earned her Medical Degree from UCLA and her Bachelor of Science in Biochemistry and Cell Biology from the University of California at San Diego.
Amal Bolis Tanagho, MDConsulting Psychiatrist
Phil Kosanovich, MBAPresident & Chief Executive Officer
Phil has a senior leadership profile that spans from entrepreneurial ventures to global corporations. His experience includes consulting, operational, and executive-level roles in the behavioral health and addiction treatment industries that include co-founding and growing two residential and outpatient treatment centers. Phil is an inclusive and transformational leader with a reputation for building strong client/patient-centered teams focused on clinical excellence. He has an extensive record of success in leading companies through transitional periods of growth and creating and maintaining strong external partner relationships.
Phil’s expanded healthcare industry experience was with Landauer, where he started two subsidiary companies and led company operations in Australia and China. Prior to his 30 years in the healthcare industries, Phil was president of human resource and financial services related subsidiaries of Travelers, Equitable, Lincoln Financial Group, and Chicago Title & Trust. He has served on the executive board and in multiple leadership roles of a global human resources trade organization and elected into that industry groups Hall of Leaders. Phil has served on the boards of several healthcare-related charities and is the Chair of the Community Relations Commission in his hometown. Phil earned an MBA from DePaul University and a Bachelor of Science in Business Administration from Valparaiso University. He is in long term recovery.
Jessica StoneCo-Founder and Executive Assistant
Since Cornerstone’s inception, Jessica Stone has been an integral component of the family business. Co-founding it in 1984 with Michael, she has tirelessly dedicated her life to the improvement of recovery outcomes for thousands of addicts.
Born in India, she grew up in the UK where she met and married Dr. Stone in 1967.
Jessica is extremely proud of her three children, Simon, Samantha and Tim, who have also dedicated their lives to Cornerstone and the treatment of addictive disorders. Like her husband, she is a doting grandmother of her five grandchildren.
Samantha Stone, BAExecutive Vice President
Samantha (likes to go by Sam) graduated from California State University, Fullerton with degrees in Psychology and Sociology. She has been with Cornerstone since its conception in 1984. She started in the Business office sending out insurance claims and collections. After that she moved to Admissions and Intake. She has spent most of her career in Intake/Admissions talking to potential patients and families about the programs at Cornerstone and what to expect. From Intake she moved into Management with becoming the Senior Vice President then President in 2019.
Sam has love for all animals especially dogs and cats. She loves hiking, road-biking, movies, theater, traveling, and different cuisines.
Simon A. Stone, BAExecutive Vice President, Safety Officer, Corporate Business Development and Court Liason
Along side his duties as Senior Vice President of the company, Simon acts as Cornerstone’s Safety Officer. His main role addresses continuous quality improvement and management of Cornerstone estate. He ensures that the property is continuously well managed and that the facilities are up-to-date, comfortable and safe for our many clients, staff, and visitors.
Simon also assists in our Alternative Sentencing Program, where he passionately advocates for treatment in lieu of jail time in conjunction with criminal defence attorneys, public defenders, district attorneys, judges and commissioners.
He enjoys surfing, traveling in his “sports mobile” and raising four beautiful children, four turtles, five fish, one dog, one cat, and one hamster, always with the constant support of his wife, Kari.
Timothy Stone, BAExecutive Vice President
Tim Stone has been part of the Cornerstone Team since 1999. He began his career assisting with the upkeep of the Recovery Residences that he now oversees. Tim’s responsibilities include ensuring that Cornerstone’s Recovery Residences are following the California DHCS, Joint Commission, and CCAPP regulations at all times. Tim is also responsible for Cornerstones IT, SEO, and overall online presence, working as the company liaison with our external expert partners in these areas. Tim is also responsible for our ‘Environment of Care’ team, which is accountable for all the on-going maintenance, repair, improvement, and housekeeping needs of the company.
Tim enjoys surfing, reading a good book, and playing guitar. He was the Lead Singer/Songwriter for the music group The Goodkind (for those interested, find them on Spotify).
Tami K. Campbell, CADC-CASExecutive Director
Regina HarrisDirector of Operations
Aryan Monroe, MA, LMFT, CSClinical Director
Mark Ballard, CADAC IDirector of Admissions
Robert C. Griffin, SPHRHuman Resources
Roxanne BatesDirector of Clinical Outreach
Roxanne blends more than 33 years of recovery and personal growth together with over three decades of account management experience. Her unique insight into the needs of those seeking treatment developed when she began her career in behavioral health as an admissions manager and continued as she spent the last several years managing clinical outreach teams. For several decades, Roxanne has used her skills and passion to improve the lives of others on their journey to recovery. She has extensive experience working directly with individuals and their families to assure they receive the appropriate care necessary to experience the promises of recovery. An expert in crisis and family interventions, Roxanne enjoys a proven record for developing and maintaining relationships within the behavioral health community and has a reputation for always keeping patients and their recovery as her first priority.
Gabrielle HilgerOperations and Clinical Support Services Manager
Lauren AgajanianAlumni Program Coordinator
David Schornack, MA, AMFTAssistant Clinical Director
Maria Carter, CADC IICase Manager
Samuel David Michael, RADTOutpatient Day Lead/Case Manager
Monnaye Bernal, MA, ACSWTherapist
Taylor Tran, AMFTTherapist
Mayra Melgoza, ACSWTherapist
Diane Shaw, CADC IIDischarge Planner
Crystal Melms, CADC II, CCDSCase Manager
Andy Kellems, CADC IICase Manager
Lietta Brutsche, CADC IICase Manager
Raul Perez, RADTCase Manager
Erin Troske, SUDRCCase Manager
Roberto Palacios, CADC ICounselor Technician
Cory Weil, RADTCounselor Tech
Marlys Wood, MS AMFT, MT BCMusic Therapist
Marlys Woods is a board-certified music therapist who has extensive experience supplying music therapy to substance abuse facilities. She has performed and taught music her entire life.
Marlys graduated from Chapman University in 2011 with a degree in music therapy and a minor in psychology, and she graduated from Vanguard University with an MS in clinical psychology. Marlys is in the process of becoming a marriage and family therapist and enjoys using her knowledge of relationships, people and music to help those who are struggling with addiction.
Marlys brings a variety of interventions such as active music making, songwriting, and lyric analysis, as well as relaxation techniques and art paired with music to her sessions. Marlys has successfully used these interventions to facilitate Cornerstone clients’ finding healthy coping skills as they move forward on their journey of sobriety.