New testimony identifying the Boston father-kidnapper with multiple personalities as a German exchange student in 1980 left investigators sure of only one thing about him: he is not Clark Rockefeller.

"We're already familiar with multiple aliases. If there's one thing we're certain about this suspect, it's that his true name is not Clark Rockefeller," Jake Wark, press secretary for the Suffolk District Attorney in Massachusetts, told FOXNews.com Thursday.

Rockefeller, 48, remained in a jail Thursday pending his trial on charges of kidnapping seven-year-old Reigh Boss, his daughter with British ex-wife Sandra Boss, on July 27. He insisted that his name is Clark Rockefeller and remained tight-lipped on details of his identity.

Witnesses have identified Rockefeller as a member of the elite Rockefeller family, a former director of the exclusive Algonquin Club, and a suspect in the disappearance and possibly murder of a couple from California in 1985. A new lead about his past identifies him as a German exchange student who stayed with the Savio family of Berlin, Conn.

Steve Savio, 39, told the Herald in an interview Thursday that Rockefeller was the 17-year-old Christian Gerhart Reiter who boarded with his family. However, Reiter has no record of attending Berlin High School, Savio's brother Edward, told Canoe.ca in a telephone interview from California.