(CBS) -- Modern forensic tools make it nearly impossible to commit the perfect murder and difficult to kill a human being without leaving some clue behind that can be analyzed and identified. Yet, a young, mostly self-educated German immigrant nearly did just that.
Christian Gerhartsreiter came to the United States in October, 1978, and for the next three decades, lived a life as an impostor. He pretended to be Christopher Chichester in wealthy San Marino, California, where he convinced residents there he was a member of English royalty. In 1985, he then moved to the equally posh Greenwich, Connecticut and became Christopher Crowe, a well-known Hollywood producer. Unable to give up his royalty claim, he would sometimes throw in the name "Mountbatten" for good measure.
But his most audacious transformation occurred in the mid-90's when he moved to Manhattan and "Clark Rockefeller" was born.
To hear Gerhartsreiter, an avid fan of mysteries and noir films, describe it, he was just playing various characters and wearing harmless disguises, much like people do on Halloween or at Star Trek conventions. Not so, say authorities in San Marino.
Gerhartsreiter had a much darker, more sinister motive: Gerhartsreiter was trying to get away with the perfect murder.
The crime occurred shortly before Gerhartsreiter left San Marino in 1985. He had been living in a rented guesthouse behind the home of Didi Sohus, a lonely widow who needed extra money. Didi's 27-year old son John and his wife Linda were also living in the main house when the couple suddenly disappeared. Police tried to question the tenant living in the guesthouse, a man they thought was Chichester, but when he showed up naked at the door and refused to dress, they quickly left. Shortly afterwards, Chichester, the man we now know was Gerhartsreiter, vanished as well.
When an adult disappears and there is no evidence of foul play, there's not much investigators will do. And so, John and Linda Sohus' disappearance remained a mystery until 1994. His mother was dead by then and her home was sold. A contractor, excavating the ground for an in-ground pool the new owner wanted, suddenly came across bags of bones.
John Sohus had been found.
John Sohus had clearly been the victim of foul play, but the coroner wouldn't call it homicide. Meanwhile, Linda's body was never found. Investigators searched for the primary person of interest, Chichester, but he was long gone. The missing person's case was now a suspicious death, but the trail went cold.
And then in the summer of 2008, a seemingly unrelated case gave new life to the cold case. A man by the name of Clark Rockefeller was arrested after kidnapping his daughter in Boston. A check of the suspect's fingerprints showed he wasn't a Rockefeller at all, but the "Christopher Crowe" and "Christopher Chichester" who had disappeared years earlier. The Los Angeles County Sheriff's department assigned two veteran detectives to the case, Sergeant Tim Miley and Dolores Scott.
"We had no idea how bad it was...how difficult it was gonna get," Miley told me later. Scott added, "It took four years. Four years of our lives. right?"
With Linda Sohus still missing, their job was to determine who killed her husband, John. They believed it was Gerhartsreiter, but they needed the evidence to convince a jury.
First, they had to do was determine exactly HOW John Sohus had died. When his body was recovered in 1994, the coroner ruled his injuries had been caused by blunt force trauma, but wouldn't call it a "homicide". The detectives hoped another pathologist could be more definitive, but, astonishingly, the remains were nowhere to be found. It turns out that the coroner's office had cremated them in 1995. Only the skull and a jaw bone had been saved but both were missing. After digging through evidence at the coroner's office, Detective Scott finally found the skull, only to discover that it was in pieces.
After many disappointments, however, the detectives got a break. A lab in Hawaii was able to collect enough DNA from the skull to determine that it did, in fact, belong to John Sohus. And forensic pathologist Robert Sheridan was able to examine the reconstructed skull and figure out just how John Sohus died. Analyzing the edges of the broken pieces of skull, Dr. Sheridan could distinguish between the damage that occurred when the body was excavated and trauma that occurred while John Sohus was still alive. According to Dr. Sheridan, John Sohus was hit on the back and front of his head as many as three times with great force.
When the detectives also had the victim's shirt analyzed, they found more evidence of cause of death. There were rips that appeared to be caused by a knife. Sohus had been bludgeoned and stabbed to death, but by whom? Science could only go so far. No fingerprints, no DNA, no physical evidence belonging to Christian Gerhartsreiter were found on the remains or the plastic bags used to encase them.
Gerhartsreiter appeared to have done his homework and covered his tracks, but maybe not as well as he thought. While he left no physical evidence behind, there were plenty of incriminating clues and circumstantial evidence.
In the end, it was his own behavior that brought him down.
Correspondent Erin Moriarty investigates the "Clark Rockefeller" murder case for "48 Hours" Saturday at 10 p.m. ET/PT.