BOSTON -- The search for a missing 7-year-old girl allegedly abducted by her father from Boston Sunday has now turned to New York state and the open sea, with the FBI and Coast Guard joining the hunt.

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Investigators say Clark Rockefeller, 48, may have taken his daughter Reigh down to Long Island, fleeing on a 72-foot luxury yacht named "Serenity," possibly toward Bermuda.

The New York Police Department said Rockefeller was last seen at about 7:30 p.m. Sunday at Grand Central Terminal.

Authorities searched Monday in the waters surrounding New York and Long Island. Police have been combing marinas looking for the boat, but there are several hundred boats with the same name in the area.

An Amber Alert was issued that day in Massachusetts after Rockefeller allegedly snatched the girl during a supervised visit in Boston's Back Bay neighborhood, fleeing with the child in a dark SUV driven by another man.

The social worker supervising the visit was injured trying to stop the alleged abduction.

Boston police issued an arrest warrant for Rockefeller on charges of custodial kidnapping, assault and battery and assault and battery with a dangerous weapon, the SUV.

The child has been living with her mother, Sandra Lynn Boss, who works in London as a partner in global management consulting firm, McKinsey & Co.

The couple was divorced last December and Boss legally changed her daughter’s name from Reigh Storrow Rockefeller to Reigh Storrow Mills Boss last year.

Sunday's visit was the first time Rockefeller had seen his daughter since that time.

A spokesman for the descendants of John D. Rockefeller Sr., said he could say with certainty that Clark Rockefeller was not descended from the side of the family that made billions of dollars with Standard Oil and whose name is synonymous with extraordinary wealth.

He said that family archives also show no indication that the fugitive was descended from William Rockefeller, John D. Rockefeller Sr.'s only sibling.

In a 2004 interview with a New Hampshire newspaper, Rockefeller declined to comment on whether he was related to the well-known clan.

Investigators said Rockefeller is said to be an eccentric millionaire mathematician known to use several aliases, such as J.P. Clark Rockefeller, James Frederick and Michael Brown. Authorities said he does not appear to have a job or a valid Social Security number.

He owns millions of dollars worth of property in New England, including an exclusive brownstone in Boston's Back Bay, where neighbors were still trying to sort out the story of the child's alleged abduction.

"I feel very bad for the little girl and I also, I think, in a way, feel bad for him too. I think it was kind of a desperate move on his part, even though it wasn't a wise decision," neighbor Noel Kenyon said.

Investigators said they now think the alleged abduction was planned for months.

Rockefeller married Boss on Nantucket in 1994 and the couple lived in Boston's toney Beacon Hill neighborhood. Reigh was born in May 2001, and Boss filed for divorce in 2007.

Rockefeller is a former director of Boston's exclusive Algonquin Club, but resigned from the club three months ago, the club's manager said Monday. Police said Rockefeller met his daughter and the social worker at the club's address on Sunday.