The FBI also wants people to know that Reigh wears prescription glasses, though she is not seen wearing them in any of the published photos.
The mystery behind Reigh's disappearance has only been complicated by the shady history of her father.
"Nobody knows who this guy is," a high-ranking Boston police official assigned to the task force in charge of investigating Rockefeller's background told ABC News in an exclusive interview. "He is a ghost."
Boston police said investigators have not located a valid Social Security number for Clark Rockefeller. They have also found no wedding certificate documenting his marriage to Boss, the mother of the missing child who got custody of their daughter, Reigh, after their 2007 divorce, the official said.
The task force has not found any work history for Rockefeller, who told one former neighbor in New Hampshire that he was a "physicist" and fashioned himself as a "philanthropist" who sat on the boards of various nonprofits.
Investigators also are unclear about Rockefeller's education history, the official said, despite reports that he commonly told acquaintances he attended Yale and Harvard. Some people have told authorities that Rockefeller said that his parents died in a car crash when he was young; others were told he was homeschooled as a kid.
The Boston Police Department last placed Rockefeller at Grand Central Terminal in New York City. He had told Ang that he was heading for a boat he had recently purchased, a 72-foot catamaran called Serenity.
Boston police detectives have been sifting through stories that Rockefeller told friends in Boston about wanting to travel to Alaska, Peru and Bermuda on the yacht, according to a high-ranking police official with direct knowledge of the case.
Late Tuesday, Boston police released two photos of dresses they believe Rockefeller may have purchased on Sunday before the alleged kidnapping.
A Delaware woman came forward Tuesday and reported seeing a well-dressed man who matched Rockefeller's description and was with a young girl at a car dealership. The sighting has not been confirmed, but authorities are investigating the report.
Rockefeller, who has been connected to several aliases, is not a descendant of John D. Rockefeller, the wealthy New York industrialist, but he apparently did not dissuade other people from assuming they may be related.
When the Rev. Brian Marsh of Trinity Church in Cornish, N.H., where Rockefeller and Boss attended church until about two years ago, asked about Rockefeller's famous last name, he said Rockefeller didn't answer him directly.
Instead, he took out a pocketknife with the name "Nelson Rockefeller" on it, Marsh said. "He implied a connection."
Other neighbors in Cornish, a former artist's colony where Rockefeller and his wife Sandra purchased a historic property, described the kidnapping suspect as "elusive" and "vague" about personal details. They said he was a doting dad, but described him as paranoid, noting that he built a mote around the property and set up a security perimeter.
Rockefeller, known for his preppy attire, also boasted an extensive art collection that he said included several original works by Mark Rothko.
Rockefeller and Boss, who reportedly married in the early 1990s on the Massachusetts island of Nantucket, divorced in 2007. A judge impounded the divorce case file at the couple's request.