Major J. Mark Heisey, USMC (Ret.), a beloved husband, father, and grandfather, passed away unexpectedly on March 11, 2026, at Avera Hospital in Sioux Falls, South Dakota, surrounded by his wife, brother, and children. He was 65 years young.

Visitation will begin at 4:30 pm, with a Time of Remembrance starting at 6:00 pm on Friday, March 20, 2026 at Miller Funeral Home (Southside Location) 7400 S. Minnesota Ave, Sioux Falls, SD.

To watch the Time of Remembrance,  click here:    https://youtube.com/live/FqmwyLBvrRc?feature=share

A Celebration of Life and Military Rites will be held on Saturday, March 21, 2026 at 10:30 am at The South Dakota Military Heritage Alliance, 1600 W. Russell St. Sioux Falls, SD, followed by a luncheon and additional visitation.

Born John Mark Heisey to John and Susan Heisey in Lancaster, Pennsylvania, on September 6, 1960, Mark grew up on the family farm in Mount Joy, Pennsylvania. He completed high school in Fairfax, Virginia. Following a number of aimless years in the workforce with a first marriage, he enlisted in the United States Marine Corps as a private. The Marine Corps gave him the life he sought, providing an education that led him to become a trainer at Quantico early in his career.

As a sergeant, he earned his B.S. degree and later completed a master's in business and finance, after which he was commissioned as a second lieutenant. Mark distinguished himself academically and professionally, graduating first in boot camp and second in Officer Candidate School, and rising from private to major in 18 years. His marksmanship was honed through years of practice with his grandfather on the farm. He served worldwide, including tours in Guam and Hawaii, remarried, and built a second family.

During the Gulf War, Mark's unit was the forward element entering Iraq before air strikes and later into Kuwait. He and his team were awarded Bronze Stars for their service. Stateside, he applied his expertise at the Marine Corps Air Station's naval depot, where U.S. and allied aircraft were serviced; there, Mark recovered more than a million dollars in operational savings, a source of immense pride.
After 22 years of service, Mark retired as a major and relocated with his family to Sioux Falls, South Dakota. He joined the Transportation Security Administration as Deputy Federal Security Director for South Dakota.

Following his military service, Mark held the position of Homeland Transportation Security Administrator for the U.S. government in South Dakota until 2022. He subsequently transferred to New Mexico, where he oversaw operational enhancements at Albuquerque International Sunport within the New Mexico TSA, remaining in that role until his retirement on December 31, 2025. He was widely regarded as an exemplary leader and mentor.

Mark's personal life was rich and full. He remained a devoted Marine and was active in the Marine Corps League Detachment 659 in Sioux Falls, serving in leadership roles including commandant and adjutant. He was also a member of the American Legion, the VFW, the MIL vets committee, and the Harley Owners Group (HOG).

A passionate fan of 1970s and 1980s music, Mark cherished concerts with the love of his life, Melissa. He loved riding his Harley-Davidson—often with Melissa on the back—and enjoyed annual "cousins" road trips. His lifelong interest in coin collecting connected him to history. He delighted in researching recipes for his Traeger smoker and preparing smoked meats for family gatherings and watching the Pittsburgh Steelers. Most recently, Mark restored his father's 1955 Thunderbird convertible and had planned to drive it in the St. Patrick's Day parade.

Mark's devotion to family and friends was unwavering. The Heisey's have a long-standing tradition of adoption; Carmen was adopted into the family. His door was always open, offering a warm meal, a cold beer, or a friendly conversation. He enjoyed pool games and lively talks about the newest vinyl records he found. Mark had a rare gift for making everyone feel genuinely welcomed and deeply valued.

He is survived by his wife, Melissa of Sioux Falls, SD; children Brandon and Christopher (Nikki) (Fredericksburg, VA), Cole, and Conner (Sioux Falls, SD), Colleen and Carmen (Olympia, WA); stepchildren Jayce (Elizabeth) of Minneapolis, MN, Jared Corlett of Sioux Falls, SD, and Jesse Corlett of Brookings, SD; his father John Heisey of Lancaster, PA; his brother Joel of Washington, DC; half-sisters Lynnea (Steve) Hameloth, Naomi (Karl) Myer, Megan (Adam) Fleming, Joy (Brandon) Persinger; grandchildren Evelyn and Declan; parents‑in‑law Randy and Marcia DeWall of Mesquite, NV; sister‑in‑law Jamie (Ed) Winters; brother‑in‑law Andy (Crickett) DeWall of Craig, CO; and his beloved feline companion, Bailey.
He was preceded in death by his mother, Susan, his stepmother, Linda, and his grandparents.

Memorials in Mark's memory may be sent to the Marine Corps League Detachment 659 of Sioux Falls, SD.