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 could n'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 .
Ex-wife testifies at kidnapping trial of Rockefeller impostor . Sandra Boss says she was romanced by handsome stranger . Former New York City mayor Rudy Giuliani is accused in the case. Impostor is accused of kidnapping his daughter in July .