Did Anger-Prone Boy Become 'Rockefeller'?

As authorities attempt to confirm accused kidnapper and con man Clark Rockefeller is actually German-born Christian Karl Gerhartstreiter, residents in the small German community where Gerhartstreiter grew up are talking about the young man they once knew.

In an interview with ABC News, a man claiming to be one of Gerhartstreiter's childhood friends in Bergen, Germany, described his former classmate as a bright and clever, but spoiled young boy -- a loner with a sometimes violent temper.

The childhood friend, who asked not be identified by name, said he knew Gerhartstreiter from age five to 14. Their grandmothers were close friends and the two boys went to school together until sixth grade, according to the man.

The friend told ABC News that the possibility Gerhartstreiter was living in the United States under several different aliases did not shock him.

Rockefeller continues to remain a mystery as he sits in a Boston jail cell, where he is held on charges of abducting his 7-year-old daughter Reigh during a supervised parental visit in Boston on July 27.

Authorities unraveling Rockefeller's byzantine back story believe that he swooped into Southern California high society in the mid-1980s under the name of Christopher Chichester, only to leave as a person of interest in the disappearance of a newlywed couple he lived with. Before that, he apparently arrived in Connecticut from Germany for an exchange program in 1978 as Christian Gerhartstreiter, police sources say.

"It has grown abundantly clear that Christopher Chichester is Christian Gerhartsreiter," a high-ranking Boston police official with direct knowledge of the investigation said this past week. "It appears that Clark Rockefeller is also Gerhartsreiter."

It came to light Friday morning that Rockefeller's birth brother appears to have been located in Bergen, Germany, according to separate reports published in The Boston Globe and Boston Herald.

Shown several pictures of Clark Rockefeller that have circulated since the child's alleged abduction sparked an international manhunt, a man identified as Alexander Gerhartstreiter said that he was shocked to learn that his brother had been found.

Gerhartstreiter said that his brother, Christian Gerhartstreiter, was born in Siegsdorf and raised in the same house in Bergen, where their mother continues to live today. He left for an exchange program at a Connecticut high school in 1978.

Gerhartstreiter said that before he cut off all communication with his family in 1986, his older brother told the family that he had changed his name to Christopher Chichester, the Herald reported.

ABC News' attempts to contact Alexander Gerhartstreiter and his mother over the weekend were unsuccessful.

A neighbor, Frau Helga Hallweger, told ABC News that Christian and Alexander Gerhartstreiter's mother is a recluse and that Christian did not make much of an impression on her during his youth.

She described Alexander as a nice man, and recalled that he did major research a few years back in an unsuccessful attempt to track down his brother in the United States.

With little still firmly known about Rockefeller's true identity, clues about a possible previous life in Germany are aiding investigators as they wade through the decades of aliases and apparent deceptions.

Swirling around the mystery are the 1985 killings of a newlywed couple in San Marino, Calif. Rockefeller, then apparently known as Chichester, was reportedly living with newlyweds Jonathan and Linda Sohus, when they went missing. Chichester himself went missing and the case was put on hold until human remains were found buried in the couples' pool nearly 10 years later.

While the childhood friend from Germany does not think his former schoolmate was capable of planning a premeditated murder, despite his temper, he does remember Gerhartstreiter having an obsession with weaponry.

Gerhartstreiter owned air guns that he would aim and fire at a local church, the former friend said. The pellets would usually just bounce off the windows -- though once, the friend recalls, Gerhartstreiter used a more powerful air gun that actually smashed a window.

He claimed Gerhartstreiter continually bragged about an assortment of handguns and rifles that his father owned. The friend believed Gerhartstreiter was lying, because he was never able to produce any of the guns.

The childhood friend considered Gerhartstreiter a self-absorbed loner, adding that his mother, aunts and grandmother appeared to spoil him. He believed Gerhartstreiter's father, a graphic artist and landscape painter, was the only one who did not indulge the boy.

ABC News' Michelle McPhee and David Schoetz, and The Associated Press contributed to this report.