Clark Rockefeller Impostor Case: Closing Arguments Underway in Murder Trial

April 8, 2013— -- A German conman who posed as a Rockefeller is a seasoned manipulator who made mistakes that revealed he is the killer in a decades-old cold case murder of a California man, a Los Angeles prosecutor told a jury today.

Christian Karl Gerhartsreiter, who lived for years under the name Clark Rockefeller, "always had a lie in his back pocket to explain things," said Los Angeles Deputy District Attorney Habib Balian in his closing argument. "Who can live without leaving a paper trail in today's day and age? Even the mastermind couldn't do it. Even he slips up."

Gerhartsreiter, 52, is charged with murder in the 1985 killing of John Sohus, the 27-year-old son of his former California landlady. Sohus and his wife Linda both went missing in 1985. John Sohus' remains were discovered in 1994 in the backyard of the family's San Marino, Calif., home, but no trace of Linda has ever been found.

Balian has spent the last three weeks presenting circumstantial evidence and trying to paint Gerhartsreiter as a killer. While Gerhartsreiter is only charged with killing John Sohus, the prosecutor has been allowed to say he believes the conman also killed Linda Sohus.

"This case is about two people who lived and died," Balian said in detailing the newlyweds' disappearance. "They're dead. They're dead."

There was no motive presented for why Gerhartsreiter would want to kill either Linda or John Sohus. Balian acknowledged there are no eye witnesses or physical evidence to connect Gerhartsreiter to the murder but said "circumstantial evidence is just as powerful."

Defense attorney Jeffrey Denner, who will give his closing argument later today, is expected to say his client, Gerhartsreiter, lied about his life and made up wild stories but is not a murderer. The defense also has argued that it is just as possible that Linda Sohus killed her husband.

Gerhartsreiter pled not guilty and chose to not testify in his own defense. If convicted, he faces 26 years to life in prison.

But this not the first time Gerhartsreiter has found himself in a court room. In fact, his storied past is full of bizarre and complicated twists.

After arriving in the United States in 1978 at age 17, Gerhartsreiter, originally of Siegsdorf, Germany, took on several idenities to charm his way into wealthy American high society circles, according to court documents. He claimed to be a cardiologist, a Hollywood producer and a Wall Street venture capitalist. He also boasted he was a physicist, an art collector, a ship captain and a distant descendent of British royalty.

Since the early '90s, he has gone by the name Clark Rockefeller, claiming to be an heir to the famous family's fortune, and even fooling his ex-wife about his true identity for years during their marriage.

In 1985, prosecutors argued, Gerhartsreiter was using the name Christopher Chichester and was living in the Sohus family guest house at their San Marino home. During his stay, John Sohus and his new wife Linda told friends they were going to New York on a trip, but never returned. Then Chichester also vanished.

In May 1994, about a decade after the Sohus' disappearance, the new owner of the Sohus' family home discovered skeletal remains in the backyard while digging a swimming pool.

Two years ago, in 2011, authorities confirmed for the first time the bones belonged to John Sohus, using DNA provided by his sister, Lori Moltz. The premature technology of DNA testing back in the '90s and the fact Sohus was adopted as a child delayed the definitive identity of the remains.

By 1993, Gerhartsreiter had taken on the name Clark Rockefeller and was living in New York, prosecutors said. It was then that he met Sandra Boss, who testified she was introduced to him as Clark Rockefeller and never knew him by any other name. The couple married in 1995 and their daughter, Reigh, was born in 2001.

Boss testified last week that after their daughter was born, her husband became "an unpleasant human being who was choosing not to work" and a constant liar. As the family breadwinner, Boss said she was earning $1.2 million a year at a management consulting firm in New York and her bank account and the family finances were controlled by her husband.

In January 2007, Boss filed for divorce. It was during the divorce proceedings that Boss said Gerhartsreiter's true identity began to unravel, according to court documents. When the divorce was finalized in December 2007, Boss and her daughter moved to London and Gerhartsreiter was granted supervised visitation rights.

In September 2008, Gerhartsreiter was arrested and charged with kidnapping their then-7-year-old daughter and assaulting a social worker with a dangerous weapon during a post-divorce, supervised visitation in Boston.

He was convicted and sentenced to five years in a Massachusetts state prison the following year. While serving his prison term, Gerhartsreiter was extradited to California to stand trial for the murder of John Sohus.

ABC's Dean Schabner and Maria Nikias and the Associated Press contributed to this report