For nearly 30 years, Tampa millionaire Douglas "Diesel" Cone ran one of Florida's most powerful road construction companies. He also ran something else: two complete families who had no idea the other existed.
Known as "Diesel," Cone was a self-made Tampa millionaire whose company, Cone & Graham, won over $212 million in state contracts building I-4, the Suncoast Parkway, and Gunn Highway. He was respected, well-connected, and seemingly devoted to his family.
Jean Ann Cone was a beloved Tampa socialite and philanthropist — spirited, fun-loving, and deeply generous. She raised champion bulldogs, threw legendary parties, and was described by friends as someone who lit up every room she entered. She and Douglas had been married since 1951.
Hillary Carlson lived on a secluded 67-acre gated estate in Lutz, north of Tampa. She had two children and a husband, Donald Carlson—a man she told friends worked a sensitive government job that required frequent, lengthy travel.
Both Jean Ann and Hillary sent their children to Berkeley Preparatory School. Both served simultaneously as school trustees. Both had facilities named in their honor: the Jean Ann Cone Library and Carlson Field for baseball. Both drove Rolls-Royces. Neither knew why they had so much in common.
Public records, however, showed no trace of a "Donald Carlson" linked to Hillary. But neighbors who were shown a photo of Douglas Cone immediately recognized him as "Don" — the man who lived on the estate. He had invented an entire identity, complete with a fake career, to cover his tracks.
Cone kept both worlds from colliding by being gone most weekdays from each home. To Jean Ann's world, he was a busy executive. To Hillary's world, he was a government operative. For nearly 30 years, no one questioned it — not even the housekeeper who worked for Jean Ann for decades.
In the late 1970s, Hillary worked as a secretary at one of Cone's companies. That is believed to be how the relationship began — a boss and employee affair that quietly grew into a second household, a second set of children, and a second life.
One evening, Jean Ann was found by her daughter, Julianne, slumped behind the wheel of her Rolls-Royce in their closed garage. The engine of the car was still running. Douglas was out of town. A medical examiner ruled it accidental carbon monoxide poisoning and also noted a blood alcohol level of 0.18 (over twice the legal driving limit).
Just 14 days after Jean Ann's death, Douglas Cone and Hillary Carlson were quietly married at the Sumter County courthouse. Tampa society only found out when a local paper printed a routine marriage announcement. That's when everything unraveled. Family members, neighbors, and community members all realized Douglas/Don had been living a double life for 30 years.
Douglas Cone, Jr. retained a Tampa attorney to raise concerns about his mother's death and her substantial financial assets. The family asked police to reinvestigate. Detectives found no evidence of foul play. Investigators said she likely fell asleep with the car running. Her daughter said she often closed the garage door immediately after driving inside, often before turning off the car, for security purposes. While the sad situation wasn't sinister, it unleashed an even larger emotional shock to the family. The father had been living another double life, complete with a whole other family.
Jean Ann's daughter, Julianne McKeel, gave only one public statement: "My mother died; my father made a mess. And we all just want to be left alone about it." Douglas Cone's children have been estranged from their father ever since.
Hillary Carlson spent nearly 30 years believing she was in a relationship with a government contractor named Donald. She wasn't a knowing participant in the deception. Her friends and acquaintances maintain she was also a victim of it. If she knew of another woman, she would have ended the relationship, they said. The Cones' daughter didn't know of the 2nd family either. After the marriage became public, neither she nor Douglas ever gave a statement.
Friends revealed that Jean Ann had quietly run something she called the "Cone Charity" — a fund she maintained with Tampa veterinarians, unbeknownst to Douglas. If someone wanted to adopt an animal but couldn't afford the fees, she'd simply say: "Charge it to the Cone Charity, but don't tell Doug."
Douglas Cone's double life made him one of Tampa's most infamous figures. But the people who loved Jean Ann refuse to let his scandal be her legacy. They want her remembered as she was: generous, spirited, and quietly doing good — even when nobody was watching. Douglas Cone, Sr., eventually died in 2014 at the age of 86. The family still refused to give comments to newspapers about his colorful life.
