David Martin Cassell

David Martin Cassell, age 64, left this world too soon on May 28, 2025, in Spring Hill, Tennessee. Born in Kingsport, Tennessee, David was the beloved son of the late Carl and Virginia Smith Cassell.

A proud graduate of Gate City High School, David was known for his talent and tenacity as an All-Star football player. He continued his education at Tusculum University in Greeneville, Tennessee, where he earned a Bachelor of Arts in Business. With a determined spirit and an entrepreneurial drive, David founded Dynamark Security in 1990. Through his leadership and vision, the company grew into a successful and thriving business that continues his legacy today.

Beyond his professional accomplishments, David will be remembered most for the warmth in his smile and the depth of his devotion to those he loved. He was a dedicated father who poured himself into every chapter of his daughter’s life—from coaching her grade school basketball team to proudly attending every cheer competition. As she became a mother herself, David found immense joy in doting on his three beautiful granddaughters, who lit up his world.

He is survived by his daughter, Lindsay Harlan; his life partner of 37 years, Karen Cassell; his brother, Gerald Cassell; his close friend, Ted Hibbs; and several extended family members. His presence, love, and unwavering support will be deeply missed by all who knew him.

David leaves behind a legacy of kindness, dedication, and strength—a life well-lived and deeply loved.

The care of Mr. David Martin Cassell has been entrusted to Spring Hill Memorial Funeral Home. To share words of comfort and condolences, please visit www.springhill-memorial.com