The mystery of a man calling himself Clark Rockefeller, who is accused of kidnapping his daughter and could have at least a dozen different aliases, may be solved now that a German man identified him as his long-lost brother in a photo.

Alexander Gerhartsreiter said that Rockefeller is his older brother, Christian Karl Gerhartsreiter, when shown a photograph by a Boston Herald reporter visiting his house in Upper Bavaria.

"It seems you found my brother," Alexander Gerhartsreiter told the Herald. "It is really a shock."

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He said Christian left home as a teenager and cut ties with the family about 20 years ago.

Police have been investigating whether Christian Gerhartsreiter, a German exchange student who lived with two Connecticut families, and Clark Rockefeller are one and the same.

Detectives allege Rockefeller is a con artist who has for decades been traveling across the United States, concocting different stories and using different aliases in order to live a lavish life.

Among the personas he has adopted are that of a wealthy, educated member of the elite Rockefeller family and a tenant renting a carriage house in Los Angeles County who mysteriously vanished along with the newlywed owners of the property in what became a cold homicide case.

Alexander Gerhartsreiter said Christian is his older brother and was born in Siegsdorf, Germany, on Feb. 21, 1961. He was raised in the house where the family still lives until 1978 and then moved to Connecticut as a student, never to return home again.

At first, Christian stayed in touch but then lost contact and hasn't called his parents since 1985, his brother said.

"I think Germany was too small for him," Alexander Gerhartsreiter told a Boston Globe reporter who also visited him. "He wanted to live in the big country and maybe get famous. Now that I see all this, he's really famous."

Click here for more on this story from the Boston Herald.

Thomas Seidel, the principal of the school in Traunstein, Germany, that Gerhartsreiter reportedly attended, confirmed to FOX News that Christian Gerhartsreiter was a student there.

Germany's BKA, the equivalent of the FBI, told FOX that they have no criminal record associated with anyone by that name and referred questions about his nationality to local authorities.

The 48-year-old balding father with big, round glasses and piercing eyes sits in a Boston-area jail on charges he kidnapped his 7-year-old daughter Reigh and allegedly planned to start a new life in Baltimore as Charles "Chip" Smith.

Investigators have been working to unravel the true identity and background of the man calling himself Clark Rockefeller since he allegedly snatched the little girl also known as "Snooks" from a Boston street during a supervised visit July 27.

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.

Police may well have a real-life "Talented Mr. Ripley" on their hands — mystery man, multiple identities, a taste for high society — if their theories of his web of lies and false identities prove true.

"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.

But for now, the prosecutor isn't saying much about the baffling case.

"I can only say that the investigation remains very active and is growing more focused by the day," Wark said.

He did say that, by his count, Rockefeller has "at least a dozen" different aliases.

"It's a long list," Wark said.

Rockefeller and his attorney have been mum on who he is, who he has claimed to be and where he comes from. Rockefeller refuses to speak to detectives from Los Angeles and Boston or to the media, and defense lawyer Stephen Hrones says his client won't start spilling the beans any time soon.

"I'd be a fool to let him talk." Hrones told FOX News. He said he has no reason to believe his client is anyone other than Clark Rockefeller.

Authorities have said they have no record of Rockefeller before 1993, and he claims he has no memory of his life before then.

The most recent potential alias to surface — which, if his brother is right, may be Rockefeller's true identity — is that of an "odd" 17-year-old German exchange student named Christian Gerhartsreiter who stayed with two families in Berlin, Conn., nearly 30 years ago.

Gerhartsreiter lived with the family of Edward Savio before moving to California, Savio told the Herald.

"He made my mom really nervous," said Savio, 45. "He said he was from Bavaria. We were a modest, middle-class family and he would say things like, 'I would never live like this.' He knew where the line was and he flirted with it."

An 82-year-old librarian, who also hosted Gerhartsreiter, has not-so-fond memories of the exchange student.

"He really was an odd kid," she told the Herald on condition of anonymity. "We did not really end up on a happy note. ... He had some fantastic stories about his parents. It turned out he was from a poor, working-class background."

In California, a tenant of Jonathan and Linda Sohus of San Marino who called himself Christopher Chichester and lived in the carriage house on their property, ingratiated himself to the town's elite — joining the local rotary club and speaking with a slight British accent.

The remains of a man believed to be John Sohus were unearthed on the property about 10 years after the 1994 disappearance of the couple and their guest, when the new residents were digging a space for a swimming pool. Sohus' adopted sister Ellen Sohus said a complete skeleton was found.

"My brother was bludgeoned, dismembered and buried in the backyard in three separate bags," she told MyFOXBoston.com. "There was a huge blood stain on the concrete floor of the guest house in my brother's home. My brother's car turned up on the East Coast when Chichester tried to sell (it)."

Click here for more on this story from The Los Angeles Times.

The Rockefeller link turned up after his fingerprints matched those with a license application for a Christopher Chichester. Los Angeles police sent two investigators to Boston to try to question Rockefeller in jail and named him a "person of interest" in the cold case.

The Boston Globe, citing an unnamed source, said the fingerprint also matched one submitted on a stockbroker license application filed by Christopher Crowe, believed to be another alias of Chichester, who has not been seen since the Sohuses disappeared.

In Boston, Rockefeller married Harvard Business School graduate Sandra Boss.

The couple lived in a tony brownstone, had their daughter Reigh together and led a privileged lifestyle, buying a yacht and a summer mansion in New Hampshire and hobnobbing with the area's rich and influential. Their 2007 divorce was brought on in part, court records show, by the fact that Rockefeller refused to reveal his true identity.

After Rockefeller, a former director of the exclusive Algonquin Club, allegedly ran off with Reigh to Baltimore, he used the name Charles "Chip" Smith to buy an apartment, police said.

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.

Click here for more on this story from MyFOXBoston.com.

FOX News' Greg Palkot and The Associated Press contributed to this report.