BOSTON, Massachusetts (CNN/In Session) -- The former wife of a man accused of kidnapping their daughter told a jury Monday about the unraveling of her 12-year marriage to a man she thought was a member of the moneyed Rockefeller family.
Sandra Boss testifies about the 12 years she spent with a man she thought was one of the Rockefellers.
Financial consultant Sandra Lynn Boss, 42, was stone-faced and repeatedly referred to her former husband as "the defendant" as she took the witness stand Monday at his kidnapping trial. She now lives in London, England, with the girl, Reigh, who just turned 8.
Her former husband, German-born Christian Karl Gerhartsreiter, 48, is accused of kidnapping their daughter in July, and taking the child to Baltimore, Maryland, where he'd bought a townhouse near the harbor. His trial began last week in Boston, Massachusetts.
Gerhartsreiter is charged with the kidnapping of a minor by a relative, assault and battery, assault with a dangerous weapon and furnishing a false name to a law enforcement officer. His defense attorneys told jurors they will present evidence that Gerhartsreiter was mentally ill.
As she began the narrative of their whirlwind romance and 12-year marriage, Boss described how she was charmed by a handsome stranger she knew as Clark Rockefeller, who was host of a party based on the mystery game Clue.
Boss testified that she came to the party dressed as the character "Miss Scarlet" and fell for him immediately during the summer of 1993, when she was a student at Harvard's business school.
"I thought he was very attractive," she testified. "He was very well dressed, very fit. I thought he was very polite and could talk about anything, and also very charming."
She told jurors that the man she married in 1995 told her he grew up in a townhouse on Manhattan's prestigious Sutton Place, that he had suffered amnesia and couldn't speak after falling down a flight of stairs as a child, and that his parents had been killed in an accident when he was in college.
He also said he attended Yale University under an early admissions program when he was 14 and helped foreign governments renegotiate their debt. She believed it, she said, because "he was one of the most intelligent people" she'd met.
Boss said he proposed to her during the spring of 1994, during a trip to Maine. They were married in a Quaker ceremony on Nantucket soon after she graduated from business school. Only eight people attended -- and not a single Rockefeller. Her new husband explained that he'd had a falling out with his family.
The newlyweds set up housekeeping in New York. During the early days of their marriage, she said, her husband was very supportive, but his demeanor soon changed. He became possessive and controlling, she said.
Later, he "began to show temper," she said. "He wanted to walk me to and from work every day. He began to be less supportive of my seeing my friends," she said. His criticism of her friends left her confused and in tears, she said.
By early 1996, she said, "It became a very stressful relationship from my point of view." The couple moved to Nantucket, then to Woodstock, Vermont, then back to Nantucket before buying a house in Cornish, New Hampshire.
The marriage did not improve. By the summer of 2000, Boss said she was considering a separation. She spent more time in New York away from her husband, but he wooed her back.
In September, Boss learned she was pregnant and vowed to work at the marriage for the sake of their child. Their daughter, Reigh, was born in May 2001.
After hiring two nannies, Gerhartsreiter said he could do a better job and became the primary caretaker. In September 2004, Boss transferred to her company's Boston office to cut her commute time so she could spend more time with Reigh.
The marriage ultimately fell apart and the couple separated in January 2007. Boss had always been the sole income earner and said she began to doubt that her husband was really a Rockefeller.
She said she hired a private investigator who came up with little information about "Clark Rockefeller." Shortly after that revelation, Gerhartsreiter agreed to give Boss full custody of Reigh. He received $800,000, two cars and her engagement ring.
Boss and Reigh moved to London in late December 2007. Gerhartsreiter did not respond to e-mails or calls from his daughter, Boss said, and never initiated contact with her during the first six months after she and her mother moved to London.
On July 27, 2008 -- during the first of three annual supervised visits in Boston -- Gerhartsreiter allegedly abducted his daughter, nicknamed "Snooks."
Boss described reuniting with the child at the FBI field office in Baltimore after Gerhartsreiter's arrest a week later. She said Reigh had lost weight and "seemed younger."
Boss returns to the stand on Tuesday, when she will undergo cross-examination.