
The Cornerstone Team
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 tea, many wanting to work for us because of our exceptional working conditions, camaraderie and sense of community.
- Doctors
- Board of Directors
- Leadership
- Clinical & Case Management
- Admissions/Intake Staff
- Medical Staff
- Environment Of Care
- Behavioral Health Technicians
Doctors

Michael Stone, MD, FAAFP, ABAM, FASAM
Founder and Chief Medical Officer

Michael Stone, MD, FAAFP, ABAM, FASAM
Founder and Chief Medical Officer
Dr. Stone founded Cornerstone of Southern California in 1984 when he recognized that many addicts who needed help could not afford prolonged hospital stays. Being well versed in the treatment of addiction, he also understood that the sterile conditions of a hospital setting were so far removed from the addict’s normal life, that they were not conducive to long lasting recovery. Deciding to rectify this he set up Cornerstone of California.
A place he could offer addicts seeking recovery a safe, non judgmental space where they could learn about the disease of addiction, understand their triggers, look deeper, through various empirically tested therapeutic methods, at the core reasons for their illness, while living amongst other people in a community where they could relearn basic living skills and how to socially interact. Dr. Stone has treated over 80,000 addicts and their families’ since 1969. He is well known and respected in the professional community.
Dr. Stone has refused to allow Cornerstone, or himself, be pigeon holed or type cast. He has treated individuals from all walks of life. His priority is setting the individual on the path to successful, long lasting recovery, regardless of whether they are a celebrity or homeless.
Dr. Stone graduated from Sheffield University Medical School, England in 1967. In 1969 he opened and directed the first in-hospital drug and alcohol treatment center in Canada. He then became Medical Director of Care Unit Hospital, Orange County, a famous psychiatric hospital. During his employment at Care Unit, the prevalence of alcoholism and drug addiction increased exponentially.
Dr. Stone’s experience and ability were highly esteemed and he was asked by Betty Ford if he could, along with his team, train the Directors at the Betty Ford Center by Mrs. Betty Ford.
Dr. Stone has committed himself to help people with addictive diseases for over 50 years. He has had extensive training in the field of addiction and is board certified in family medicine, board certified by the American Board of Addiction Medicine and a diplomat of the American Academy of Pain Management.
Personal Life:
Dr. Stone has been married since 1967. He is extremely proud of his three adult children who work full-time at Cornerstone. He enjoys the beach, loves dogs, and reads science fiction novels in his free time. He is a doting grandfather to five grandchildren.

Jiseung David Yoon, MD, MPH
Physician

Jeanette Ponce, MD
Physician

Jeanette Ponce, MD
Physician
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, MD
Consulting Psychiatrist
Board of Directors

Michael Stone, MD, FAAFP, ABAM, FASAM
Founder and Chief Medical Officer

Michael Stone, MD, FAAFP, ABAM, FASAM
Founder and Chief Medical Officer
Dr. Stone founded Cornerstone of Southern California in 1984 when he recognized that many addicts who needed help could not afford prolonged hospital stays. Being well versed in the treatment of addiction, he also understood that the sterile conditions of a hospital setting were so far removed from the addict’s normal life, that they were not conducive to long lasting recovery. Deciding to rectify this he set up Cornerstone of California.
A place he could offer addicts seeking recovery a safe, non judgmental space where they could learn about the disease of addiction, understand their triggers, look deeper, through various empirically tested therapeutic methods, at the core reasons for their illness, while living amongst other people in a community where they could relearn basic living skills and how to socially interact. Dr. Stone has treated over 80,000 addicts and their families’ since 1969. He is well known and respected in the professional community.
Dr. Stone has refused to allow Cornerstone, or himself, be pigeon holed or type cast. He has treated individuals from all walks of life. His priority is setting the individual on the path to successful, long lasting recovery, regardless of whether they are a celebrity or homeless.
Dr. Stone graduated from Sheffield University Medical School, England in 1967. In 1969 he opened and directed the first in-hospital drug and alcohol treatment center in Canada. He then became Medical Director of Care Unit Hospital, Orange County, a famous psychiatric hospital. During his employment at Care Unit, the prevalence of alcoholism and drug addiction increased exponentially.
Dr. Stone’s experience and ability were highly esteemed and he was asked by Betty Ford if he could, along with his team, train the Directors at the Betty Ford Center by Mrs. Betty Ford.
Dr. Stone has committed himself to help people with addictive diseases for over 50 years. He has had extensive training in the field of addiction and is board certified in family medicine, board certified by the American Board of Addiction Medicine and a diplomat of the American Academy of Pain Management.
Personal Life:
Dr. Stone has been married since 1967. He is extremely proud of his three adult children who work full-time at Cornerstone. He enjoys the beach, loves dogs, and reads science fiction novels in his free time. He is a doting grandfather to five grandchildren.

Phil Kosanovich, MBA
President & Chief Executive Officer

Phil Kosanovich, MBA
President & 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 Stone
Co-Founder and Executive Assistant

Jessica Stone
Co-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.
Personal life:
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, BA
Executive Vice President

Samantha Stone, BA
Executive 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.
Personal Life:
Sam has love for all animals especially dogs and cats. She loves hiking, road-biking, movies, theater, traveling, and different cuisines.

Simon A. Stone, BA
Executive 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 tha...

Simon A. Stone, BA
Executive 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.
Personal Life:
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, BA
Executive Vice President

Timothy Stone, BA
Executive 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.
Personal Life:
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).
Leadership

Phil Kosanovich, MBA
President & Chief Executive Officer

Phil Kosanovich, MBA
President & 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.

Tami K. Campbell, CADC-CAS
Executive Director

David Schornack, MA, AMFT
Clinical Director

Mark Ballard, CADAC II
Director of Admissions

Maria Carter, CADC II
Inpatient Manager

Samuel David Michael, RADT
Outpatient Manager

Robert C. Griffin, SPHR
Human Resources

Alicia Lovric
Business Office Manager

Gabrielle Hilger
Operations and Clinical Support Services Manager

Lauren Agajanian
Alumni Program Coordinator
Clinical & Case Management

David Schornack, MA, AMFT
Clinical Director

Abraham Benavides
Inpatient Operations Coordinator

Monnaye Bernal, MA, ACSW
Therapist

Maria Carter, CADC II
Inpatient Manager

Samuel David Michael, RADT
Outpatient Manager

Taylor Tran, AMFT
Therapist

Nicholas Prelesnik
Therapist

Amber Hamilton
Therapist

Diane Shaw, CADC II
Discharge Planner

Crystal Melms, CADC II, CCDS
Case Manager

Andy Kellems, CADC II
Case Manager

Lietta Brutsche, CADC II
Case Manager

Juliet Macias
Case Manager

Cory Weil, RADT
Counselor Tech

Raul Perez, RADT
Case Manager

Thomas Greenwood
Case Manager

Danielle Dawson
Case Manager

Paul Vaala
Behavioral Health Technician

Erin Troske, SUDRC
Case Manager

Austin D’Amond
Counselor Technician

Marlys Wood, MS AMFT, MT BC
Music Therapist
Admissions/Intake Staff

Anya Chernitskaya, BSHS, CADC-CAS
Utilization Review

Mark Ballard, CADAC II
Director of Admissions

Stacy Elliot Johnson, BSHS, RADT
Admissions Counselor

Shiva Amirkhalili
Admissions Counselor / Legal Liaison

Jennifer Sandoval, RADT
Client Financial Advisor

Kelsey Reed
Admissions Counselor

Roberto Palacios, CADC I
Admissions Coordinator

Tahra Joseph
Admissions Counselor
Medical Staff

Danielle Graniello, LVN
Lead Nurse

Kayla Griffin, LPT
Nurse

Veronica Soni
Nurse

Maritza Nogueda, LVN
Nurse

Matthew Gomez, LVN
Nurse

Tammy Byars, LVN
Nurse

Michael Tanteh
Nurse
Environment Of Care

Michael Wahl
Environment of Care

Scott Ballard
Environment of Care

Trever Maloney
Environment of Care
Behavioral Health Technicians

Kelsie Canole
Behavioral Health Technician

Yanira Chavez
Behavioral Health Technician

John Jensen
Behavioral Health Technician

David Bravo
Behavioral Health Technician

Alex Fullen
Behavioral Health Technician

Juan Torres
Behavioral Health Technician

Kristof Vilgertshofer
Behavioral Health Technician

Paris Supry
Behavioral Health Technician

Andreana Angiano
Behavioral Health Technician

Kirk Barnett
Behavioral Health Technician

Sean Besaw
Behavioral Health Technician

Aubrey Malone, RADT
Behavioral Health Technician

Myles Scranton
Behavioral Health Technician

Julie Black, RADT
Behavioral Health Technician

Dominic De Soto
Behavioral Health Technician

Rami Khawam
Behavioral Health Technician

Destiny McCarty
Office Assistant

Madison Fugate
Behavioral Health Technician

Titus Davis
Driver

Paul Baumann
Driver
