Christian Karl Gerhartsreiter, Christopher Chichester, Clark Rockefeller: Are they the same man?

It was a story that gripped both sides of the Atlantic. An elusive millionaire who kidnapped his own seven-year-old daughter in broad daylight and escaped with her to Baltimore.

When Clark Rockefeller was arrested by FBI agents, who had staked out the marina where he was staying, he was portrayed as a devious, but ultimately harmless eccentric who longed to be accepted by the high flyers of American society.

But 10 days on, the story has taken a more sinister tone. US authorities are now convinced that Rockefeller is in fact a German citizen who is wanted for questioning over the sudden disappearance of a couple in California more than 20 years ago.

In another incredible twist to the saga, the man who conned his American friends – and even his former wife of 12 years – to believe he was a member of the famous Rockefeller oil dynasty, was "positively identified" by US police on Monday as the German-born Christian Karl Gerhartsreiter.

Investigators say that Rockefeller left his native country for the US when he was just 17, a claim which was soon reinforced by the discovery of a man living in Germany who said he was Rockefeller's long-lost brother.

Alexander Gerhartsreiter, 34, of Bergen in Bavaria, said his elder brother, Christian, left the family in the 1970s to seek his fortune in the US. He greeted a reporter carrying a photograph of Rockefeller at the door of his house in Germany with the words: "It seems you found my brother."

Mr Gerhartsreiter insists that his elder brother was born in the Bavarian municipality of Siegsdorf in 1961. As their father was an artist and their mother a housewife, he had a humble upbringing and, according to his brother, always wanted to better himself. After moving to Connecticut in 1978, he initially kept in touch with his family in Bavaria, before communications ceased in 1985.

"He's my brother, but I didn't know him," Mr Gerhartsreiter said. "I have only a few memories. He left when I was five or six. It is really a shock."

Shortly after arriving in America, it appears that Rockefeller moved to California to try his luck as an actor in Hollywood. According to his Boston lawyer, Stephen Hrones, he adopted the alias of Christopher Chichester, because "he was trying to get into the acting business and he thought it was a more appropriate name".

In 1985 – the same year he stopped contacting his German family – Rockefeller used his Chichester alias to rent a room in a guesthouse in the wealthy enclave of San Marino, near Los Angeles, where a young married couple called Jonathan and Linda Sohus were also residents.

Police files state that the couple mysteriously vanished while Chichester lived there. Not one member of the trio was ever heard of again. The case was abandoned until 1994, when skeletal remains were unearthed in the back garden of the property by its new owners, who were building a swimming pool.

At the time, police were unable to identify the remains, although they believed them to be those of Mr Sohus. Now that they are confident Chichester has finally been tracked down – living under the new alias of Clark Rockefeller – a new set of forensic tests can be carried out.

Ray Cornwall, who lived near the guesthouse, recalled that some locals were suspicious of Chichester because of several outrageous claims he made about his past, including that he was related to a famous British sailor. "It's going to be hard to prove anything because he's not left any permanent trail," Mr Cornwall said.

Similar accusations were recently levelled at Rockefeller by members of the small community of Cornish in New Hampshire, where he lived with his wife and daughter while their family was still intact. One local resident, Judith Kaufman, said that he had a "Napoleon complex" and seemed intent on becoming "the new lord of the land" by becoming as involved as possible with the running of the town. "I was suspicious from the first time I heard that he was related to the Rockefeller family," she said. "The way he wore the name on his sleeve, in a gloating kind of way, seemed unusual." Rockefeller is currently being held on kidnapping charges in Boston, where he vanished with his seven-year-old daughter, Reigh, on 27 July, sparking a nationwide manhunt, which culminated in his arrest at a Baltimore marina a week later. Reigh, who is nicknamed Snooks, had been living with her mother in London since her parents finalised their divorce. She was visiting her father under supervision during the school holidays when she was taken, but was eventually recovered unharmed and reunited with her mother.

Rockefeller has so far refused to be interviewed by Los Angeles police about his part in the 1985 disappearance case. His lawyer initially said that his client remembered only "bits and pieces" of his life prior to 1993, and nothing at all about his upbringing in Germany, although he does understand the language.

Police in the US are still unable to find any record of his existence at all before 1993, the year he began referring to himself as Clark Rockefeller, which he still insists is his real name.

He has, however, said that he used other aliases in the past, an admission which will come as no surprise to US police. Before they traced him to Baltimore, detectives investigating the kidnapping of Rockefeller's daughter were perplexed by his impressive number of alter egos, which included the names James Frederick and Michael Brown.

As a result, authorities in Boston have been reluctant to confirm that Christian Gerhartsreiter, Christopher Chichester and Clark Rockefeller are definitely the same person. "This defendant's efforts to avoid identification are simply too extensive for us to take anything at face value. One thing we are certain of – this defendant's true name is not Clark Rockefeller," said Jake Wark, a spokesman for the prosecutor's office in Massachusetts.

There can be no doubt that Rockefeller was rich – he bought a catamaran just days before his arrest, and reportedly had an impressive collection of paintings – but the source of this wealth remains a mystery. Some friends said he told them he was a mathematician or a physicist, while others believed he worked as a Wall Street financier.

In custody in Boston, Rockefeller said he does remember meeting a newly- married couple named Jonathan and Linda Sohus in California, but that he barely knew them. He apparently maintains that the couple left of their own accord and he never saw them again. According to Mr Hrones, Rockefeller said: "I'm not a violent man. I've never murdered anybody."

Many of the recent revelations are likely to be news to Rockefeller's former wife, 41-year-old Sandra Boss, who works in London as a financier for the management consultants McKinsey & Company. During the investigation into her daughter's kidnapping, it emerged that Ms Boss believed that her husband was a genuine Rockefeller, a claim which was subsequently denied by the family's archive centre.

Even the legitimacy of the couple's marriage has been called into question, after Rockefeller's lawyer hinted that his client could be forced to give back the £416,000 settlement he received when they finalised their divorce in December. They were thought to have married in Massachusetts in 1995, but no official record of the union has ever been found and it is unclear whether the couple provided a marriage licence.

"They weren't legally married," said Mr Hrones, after meeting his now world-famous client. "How can you divorce when you're not legally married?"