A simple fabulist, or a killer clever at covering his tracks?

He mixed with the well-to-do in the upscale suburb of San Marino, proclaiming himself an English baronet who taught film at USC.

He briefly settled in a wealthy Connecticut enclave, convincing locals he was a successful television producer. He talked his way onto Wall Street, persuading one firm to let him run a bond trading desk.

But it was his fraudulent claims of being a member of the famous Rockefeller family that led to his most lucrative success — and, ultimately, his downfall.

For the last three weeks, both the prosecution and defense in the downtown Los Angeles murder trial of Christian Karl Gerhartsreiter have highlighted the German native’s numerous fabrications. Both are using his history of deceit to their advantage in the case, which revolves around the 1985 killing of his landlady’s adult son in San Marino and the victim’s missing wife.

Gerhartsreiter’s use of false identities has taken on added importance to the prosecution, which is hampered by a lack of DNA or other strong forensic evidence connecting him to the killing, as well as by the faded memories of witnesses. Deputy Dist. Atty. Habib Balian has argued that Gerhartsreiter went to extreme lengths after the killing to hide his true identity from authorities, particularly when he realized detectives wanted to talk to him.

But defense attorneys point to their client’s long history of fictional tales, saying they were part of a pattern that began as soon as he arrived in the United States, years before the killing.

“They’ve proven that he’s a strange guy, an odd guy, a guy who may have tried to get things from other people, like meals and housing, but not much else,” attorney Brad Bailey told jurors.

As closing arguments begin Monday, jurors have been left with two conflicting portraits of Gerhartsreiter: one as a simple fabulist, the other as a killer covering his tracks.

Gerhartsreiter was born in 1961 in the small Bavarian town of Bergen. His father was a sign-maker and his mother a homemaker, according to one witness who met them. As a teen, Gerhartsreiter talked of leaving Germany and his interest in the film industry.

He arrived in the U.S. in 1978 at 17, eventually enrolling at a high school in Berlin, Conn.

Edward Savio’s family took him in. Savio said he liked the German student who wore tight jeans and claimed that his father was a wealthy industrialist who supplied parts for Mercedes-Benz.

Gerhartsreiter experimented with American accents, trying to perfect his speech, Savio said. Gerhartsreiter was kind to Savio and his sister, but he was dismissive of the rest of the family, telling Savio’s mother her cooking was terrible and that he “would never live like this.”

Gerhartsreiter soon enrolled at the University of Wisconsin-Milwaukee, where he dated Elaine Siskoff, a student. Siskoff recalled how he asked her to be his bride in a “sham marriage” so he could get a green card. She refused, but her sister agreed.

After the wedding, Gerhartsreiter took off, telling Siskoff he was going to California for an internship with “Star Wars” director George Lucas, she testified.

He landed in San Marino, ingratiating himself with older parishioners at an Episcopal church and bragging that he was descended from British royalty. He passed out a business card with a family crest and a new name: Christopher Chichester, the 13th baronet.

He presented a friend from church with a paper bag filled with tea, saying it was from his family’s plantation abroad. He hung around the USC film school, telling some he was a student and others he was a professor.

Though he boasted of wealth, he drove an old car and always seemed hungry, said a friend, Dana Farrar. Another friend said she could tell he was masking an accent and spoke like Thurston Howell III, the wealthy character on “Gilligan’s Island.”

Gerhartsreiter lived in a guest house at 1920 Lorain Road. The property’s owner, Ruth “Didi” Sohus, lived in the front house with her son, John, and his wife, Linda.

In early 1985, the young couple disappeared. Around the same time, Gerhartsreiter lent a white truck to a USC student, the former student testified. The vehicle’s description matched the truck the Sohuses had recently purchased.

There was other peculiar behavior, according to court testimony. Gerhartsreiter told a neighbor who complained about foul-smelling black smoke coming from his guest house chimney that he was burning carpet. He tried to sell an Oriental rug that appeared to have a small bloodstain.

When police followed up on the missing Sohuses, Gerhartsreiter came to the door of his guest house naked. George Yankovich, then a street cop, recalled in court that he asked the slim young man to put some clothes on.

“No, I’m a nudist,” was the reply.

Within months, Gerhartsreiter had moved to the affluent town of Greenwich, Conn. He masqueraded as a television and film producer, adopting the name of a real producer: Christopher Crowe.

As in San Marino, Gerhartsreiter headed for the local Episcopal church. He befriended the pastor’s son, Christopher Bishop, a film student. He introduced himself as the executive producer of the latest “Alfred Hitchcock Presents” TV series. Gerhartsreiter showed Bishop a pilot episode of the series and a poster for a movie the real Christopher Crowe had produced.

“He had it down,” Bishop said in court last week. “I was sold.”

In 1988, Bishop testified, Gerhartsreiter offered him a white truck. When Bishop attempted to get the title from California authorities, he discovered there was a lien. The truck had belonged to John and Linda Sohus.

The title check prompted San Marino police to ask Greenwich authorities to check on the truck. Gerhartsreiter was by then using a fake Social Security number and working for a series of Wall Street securities firms. When a Greenwich detective began calling his work and home, Gerhartsreiter grew paranoid, his girlfriend at the time, Mihoko Manabe, testified.

He told her he and his parents were in danger, and that he and Manabe needed to go into hiding, she said. He dyed his hair and eyebrows blond, disposed of his garbage in public trash bins and adopted various aliases.

During a trip to Maine, she said, he called their hotel’s restaurant to make a reservation under a new name: Clark Rockefeller.

“He liked the attention that he got,” Manabe said.

In San Marino, the mystery about the missing Sohuses took a macabre turn in 1994 when construction workers building a swimming pool for their home’s new owner stumbled across John’s corpse buried in the backyard.

His head had been bashed with a blunt object. Authorities found large traces of blood on the concrete flooring of the guest house where Gerhartsreiter had lived, but they could not determine whose it was.

The victim’s skull was wrapped in two plastic bags. One was a USC bookstore bag from the early 1980s. The other was from the University of Wisconsin-Milwaukee, of a type used from 1979 to 1982, when Gerhartsreiter was a student there.

On the other side of the country, Gerhartsreiter was dating a Harvard graduate business student who knew him only as the eccentric but brilliant Clark Rockefeller.

Gerhartsreiter was charming, Sandra Boss said in court. They wed in 1995. Her husband claimed he had taken care of the legal paperwork to make their Quaker wedding legal. She said she later learned he never had. His interest in Quakerism, which does not use a formal officiant at weddings, soon ended, Boss testified.

In 2001, the couple’s daughter was born.

Boss said her husband was zealous about protecting his privacy, wearing hats in public, using post office boxes and keeping official records in her name. He refused to travel to either California or Connecticut.

Boss said his early charm evaporated, and he ended up living off her income, even while claiming that he had a company that was working on space travel technology for the military.

“He was an unpleasant human being who was clearly choosing not to work,” Boss testified.

She was making more than $1 million working for the global management consulting firm McKinsey & Co., but he controlled the finances. When she told her husband she wanted to leave him, he threatened that she would never see their daughter again, she testified. They divorced in 2007.

After their separation was final, Gerhartsreiter kidnapped their 7-year-old daughter, resulting in a highly publicized manhunt that ended in his arrest and conviction for kidnapping. The case prompted California authorities to refocus on the Sohus murder file.

In a 2008 jailhouse interview with NBC’s “Today” show, which was played for the Los Angeles jury, Gerhartsreiter said he remembered growing up in New York and picking strawberries once as a child in Oregon. He knew nothing about Germany, he said.

Asked whether he killed John and Linda Sohus, he replied: “My entire life, I’ve always been a pacifist. I’m a Quaker, and I believe in nonviolence. And I can fairly certainly say that I’ve never hurt anyone physically.”

hailey.branson@latimes.com

jack.leonard@latimes.com