HARTFORD, Conn. (AP) – A Connecticut man says he is convinced the mysterious man accused of kidnapping his daughter in Boston and wanted for questioning in the 1985 disappearance of a California couple was a German student who lived with his family decades ago.

Immigration officials confirmed Thursday they have joined the investigation into the background of Clark Rockefeller, who is jailed in Boston on charges he snatched his 7-year-old daughter, Reigh, last month in an elaborately planned kidnapping.

Steve Savio, 39, of Berlin, Conn., said Thursday he is “100 percent certain” that Rockefeller is the same person who boarded with his family in 1980 under the name Christian Gerhart Reiter at age 17.

Savio said Greenwich Police interviewed his family in 1988 about a possible connection between Reiter and the disappearance of Jonathan and Linda Sohus, of San Marino, Calif. The FBI and German authorities interviewed them this week about Reiter and Rockefeller, he said.

Police have said Rockefeller, 48, snatched his daughter from a Boston street on July 27 in an elaborately planned kidnapping in which he hired two people to drive them to New York.

He was caught Saturday in Baltimore, where he had bought a home and boat. Prosecutors said 300 one-ounce gold coins and $12,000 in cash also were found in Rockefeller’s apartment following his arrest.

Reigh, known to family and friends as “Snooks,” was found in good condition in Baltimore and has been reunited with her mother, Sandra Boss.

Authorities have said they have no record of Rockefeller before 1993, and he claims he has no memory of his life before then. He had refused to talk to investigators or reporters.

FBI spokesman Damon Katz in Boston said “there is a pending investigation to determine who this guy is,” but refused to give any details. Paula Grenier, a spokeswoman for U.S. Immigration and Customs Enforcement in Boston, also said agents are helping law enforcement trying to determine his identity.

Savio said his family met Reiter after answering an advertisement in a local newspaper from a visiting German teen looking for a place to live.

Savio said when Reiter first moved in, he was sweet. After several months, however, “his true colors started showing,” Savio said.

“I recall him thinking he’s better than the rest of us,” Savio said. “I recall him telling stories about having servants growing up and like that.”

Authorities say Rockefeller is a schemer who wanted people to believe he was an heir to the oil tycoon, though the Rockefeller family says he is not.

Savio said he last saw Reiter in 1981, but said the man kept in contact with his mother, telling her he was using the name Christopher Crowe to open a production company.

Savio said the FBI interviewed his mother in 1988 after a man identifying himself as Christopher Crowe tried to sell a pickup truck in Connecticut belonging to the missing Californians, Jonathan and Linda Sohus. He apparently fled before authorities could track him down.

Los Angeles detectives say a man named Christopher Chichester lived on the Sohuses’ property, and he also disappeared. Police now say Rockefeller’s fingerprints matched those on an old license application submitted by Chichester. They also believe Chichester was one of the aliases used by Christian Gerhart Streiter.

Records show a Social Security number associated with the name Christian Gerhart Streiter – not Reiter – was issued in Connecticut about the same time Savio said Reiter lived with them.