The London-based mother of a seven-year-old girl kidnapped by her enigmatic American ex-husband in the U.S. on Sunday has posted a video on the Internet appealing for the return of her daughter.

"Clark, although many things have changed, you will always be Reigh's father and I will always be Reigh's mother. We both love her dearly and have only her best interests and well-being in our hearts. I ask you now, please please bring Snooks back. There has to be a better way for us to solve our differences than this way," Sandra Boss, 41, said on YouTube.

Clark refers to Boss' former husband Clark Rockefeller, 48, and Reigh or Snooks to her daughter. The couple divorced in December after a 12-year relationship with Boss winning custody of Reigh.

Boss, who lives and works in London, sent Reigh and a social worker to Boston, MA, Sunday to allow Rockefeller to see his daughter for the first time since the divorce. But he ran off with her.

Police hunting Rockefeller learned that the suspect uses several aliases and has a mysterious past. The only available information about him are his Manhattan address in the 1990s and a bank record under an alias.

"Nobody knows who this guy is. He is a ghost," a top Boston police official told ABC News.

The father and daughter were last seen at at New York City's Grand Central Terminal. Reports of their sighting in the Turks and Caicos island in the Caribbean, Puerto Rico, Delaware, and Brooklyn proved false.