But Gary V. Giordano's ex-romantic interests say the allure was only surface-deep.
FBI agents combed through Giordano's home Friday night in Gaithersburg, an upper-middle class Washington suburb. On Saturday, Solicitor General Taco Stein said a pink shirt and black sandals found during a search of an abandoned phosphate mine — near where Giordano told authorities Gardner disappeared — did not belong to the woman.
The exact nature of their relationship isn't clear. Gardner had a boyfriend back home in Maryland. Giordano was detained at the airport about a week ago as he tried to fly back to the U.S. after the official search had ended.
Authorities say they doubt certain aspects of his story, including whether the pair even went into the water, and they're seeking witnesses to build their case against him.
His family has stayed mum, though a close friend said he can't imagine Giordano being involved in someone's death.
Giordano has told authorities that Gardner, a platinum blonde who loved tennis and running, never made it back to shore after the two became separated. His lawyer, Michael Lopez, said Giordano tapped on Gardner's leg to signal that they should swim back after it became clear that they were being pulled out to sea. He said Giordano noticed that she didn't return to shore with him and ran to get help.
"Our client emphatically denies being involved in any malicious act concerning his friend and consequently does not consider himself a suspect," Lopez said in a statement this week.
The judge can extend Giordano's detention order for a maximum of eight days at a hearing scheduled for Monday. After that, prosecutors could ask a judge to order Giordano held for as long as 60 days while they prepare a case, but that would require more substantial evidence.
Court records and former romantic interests reveal Giordano could by turns be charming and threatening.
"He can't control his anger," his first wife, Sharon Cohen, wrote in court papers in 2001.
Giordano married Cohen in 1987, several years after earning a degree in computer science from the University of Maryland. The couple had three sons, but the relationship deteriorated. They finalized their divorce in 2003. At one point, each accused the other of abuse, with Giordano alleging that his wife struck him in the back with a steel cooking spoon during a heated argument.
She countered that he had a nasty temper, throwing phones, cursing and becoming violent with one of their sons.
Even after they divorced, court records show, the couple has argued over money, child support payments and parenting obligations for their sons — a 19-year-old and 14-year-old twins. A young man who answered the door at Cohen's house and identified himself as one of her sons said the family had no comment. Giordano's mother also declined to comment.
Court papers also indicate Giordano can be an attentive father, insisting that a son who was struggling in school devote time to his studies.
He lived close to his ex-wife and children, in a contemporary home set apart from the neighborhood by a long, ascending driveway. A sign on the front door advises visitors they're under surveillance. A security camera is mounted atop a gable.
Though his house suggests a man who values his privacy, Giordano is also gregarious and fun, said Eric Curtis, a friend who said he regularly hangs out with him in restaurants and bars. He said he's never even seen Giordano raise his voice.
"He'd talk to anybody, male or female, and within minutes, he'd have anybody laughing," Curtis said.
Giordano and his second wife divorced in 2008 after just two years. Court records don't suggest an especially acrid relationship.
In the three years since, other women he dated — many of them thin and blond like Gardner — found that their romantic relationships with him turned ugly. One woman accused him of threatening her by saying "the world would be better off without me" and of videotaping their sexual encounters without her consent. The woman met with prosecutors, but told authorities she didn't want to pursue the case, said Montgomery County State's Attorney John McCarthy.
Attorney Gail Landau, who spoke to The Associated Press on the condition that her client's name be withheld, said her client was too frightened of Giordano to move forward with the case.
She claimed in court documents that Giordano retaliated by putting letters and photos of her on her neighbors' mailboxes. He claimed she had slandered him in emails and letters and requested his own restraining order.
Steven Kupferberg, a lawyer who has recently represented Giordano, did not return calls from AP, but he told The Washington Post that the sex tape allegations were likely exaggerated.
"I suspect that there wasn't anything to the allegations in terms of illegality," Kupferberg told the newspaper.
Jeanette Farago, a former neighbor, started dating Giordano around the time of his second divorce. She said Giordano was charismatic but could become angry and possessive, though she said she never felt physically threatened. Once, he wanted to take her on a cruise but became irate when she didn't want to go, she said.
Farago said Giordano insisted on having her email password so he could ensure she was not seeing anyone else. If she said she was going to the grocery store, he would want photographic proof. Sometimes, she said, he would spy on her and text her details of her outfit so she knew he was watching. He even hid in the woods behind her home to watch her, dressing in a deer costume, she said.
"He's Mr. Perfect," she said, and then he's "totally different."
Associated Press writers David Dishneau in Frederick, Md., Ben Fox in San Juan, Puerto Rico, and Dilma Arends Geerman in Oranjestad, Aruba, contributed to this report.