While their wives drove Rolls-Royces and moved among Tampa's elite, Douglas S. Cone and Donald Carlson always seemed busy with business.

Cone, the 74-year-old millionaire owner of a highway construction company, was gone most weekdays.

Carlson was also frequently away from home -- an absence his family attributed to a sensitive government job that required him to travel for long stretches.

But those business trips masked a shocking secret: Douglas S. Cone was Donald Carlson. Cone lived a secret double life for nearly 30 years, raising two affluent families in lavish homes 20 miles apart -- one with his wife of 52 years and the other with a former employee.

By all accounts, Jean Ann Cone never suspected her husband was using an alias to carry on a relationship with Hillary Carlson, 18 years her junior. He fathered three children with his wife and two with Carlson.

The double life unraveled this spring only after Jean Ann Cone died at age 75 and Cone married Hillary Carlson two weeks later. Friends said they learned of his new marriage in Sumter County, about an hour north of Tampa, when the local newspaper printed a listing of marriages.

Interestingly, the lives of the two families bore many similarities, but nothing raised suspicions that both households were headed by the same man.

Jean Ann Cone and Hillary Carlson both circulated among Tampa's rich and powerful. They both served as trustees at Berkeley Prep, their children's prestigious school. Facilities at the school bore their names -- the Jean Ann Cone Library and Carlson Field -- after generous donations.

With his grieving children and grandchildren stunned by the development, Douglas Cone's double life became all anyone in Tampa society talked about.

"It's so mean," said Panky Snow, a lifelong friend of Jean Ann Cone who double-dated with the Cones and was a bridesmaid in their 1951 wedding. "I feel betrayed by him too."

The Cone family isn't talking. But friends say the Cones' daughter Julianne McKeel was badly shaken by her father's behavior. Her only public statement was a curt comment to the St. Petersburg Times: "My mother died, my father made a mess. And we all just want to be left alone about it."

Douglas Cone did not return telephone calls to his office, and efforts to reach Hillary Carlson were unsuccessful. The 67-acre estate he shared with Carlson and their two grown children in Lutz, about 15 miles north of Tampa, is gated and not accessible.

It is not clear when Douglas Cone met Carlson, although in the late 1970s she worked as a secretary for one of his companies. Those close to the family also don't know exactly how Cone managed to keep his secret, other than being away on business most days of the week.

Norma Gotay, the Cones' housekeeper, said she didn't have an inkling of a second family.

"All I can say is she was just a wonderful person," Gotay said. "He was as nice as she was."

Jean Ann Cone had made a name for herself as a fun-loving, spirited philanthropist whom many described as the "life of the party."

The daughter of University of Florida athlete Ashley Wakefield Ramsdel, Cone raised champion bulldogs and so loved the breed that she once threw a party for Uga, the University of Georgia mascot, at a swanky Tampa restaurant when the team was in town for the Outback Bowl.

In March she was found dead in the driver's seat of her Rolls-Royce in the garage of the Cones' 4,000-square-foot brick home.

She had last been seen alive by a friend who had escorted her home from a small social gathering and watched her drive into the garage and close the door behind her. Police believed she passed out after she had parked the car but before she turned the engine off.

Douglas Cone was out of town at the time of his wife's death. McKeel found her mother and summoned her father and police. Detectives noted that Cone was clearly distraught at the loss of his wife.

"He was really depressed. They cared about each other," said Gotay, the housekeeper. "They had been married for so many years."

Police -- who didn't learn of Cone's other relationship until it was revealed in the Times in June -- reinvestigated Jean Ann Cone's death at the request of the Cones' three children and said there was no evidence of foul play.

"The family was only suspicious because he remarried too quickly," said Tampa police Sgt. Jim Simonson, who heads the department's homicide squad. "That can be easily explained; it's not like he met the woman two weeks before."

Norman Cannella, the Tampa attorney representing Douglas Cone Jr., said the family is satisfied with investigators' findings, although it has done nothing to mend their relationship with their father.

What concerns Jean Ann's friends now is that her husband's behavior will overshadow her memory. They want her remembered as an effervescent personality, who when it came to secrets had one -- albeit a benevolent one -- of her own.

"She had a secret fund called the 'Cone Charity' with the veterinarians in Tampa," Snow said. "If people had animals they wanted to adopt and couldn't afford the fees, she would tell them [the veterinarians] just to charge it to the Cone Charity, but don't tell Doug."

For nearly 30 years, Tampa millionaire Douglas Cone headed two families -- a situation that came to light only this spring, when he married longtime lover Hillary Carlson, above, two weeks after the death of Jean Ann Cone, right.