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.