His lawyers said he is looking forward to an appeal.
Authorities said Gerhartsreiter is a German immigrant who lived another life long ago, occupying a guest cottage at the home of Sohus' mother in San Marino, a wealthy suburb of Los Angeles. He was known then as Chris Chichester and intimated he was of royal lineage. He joined a church, befriended residents, and told some he was a film student.
A friend said Linda Sohus once described the tenant in the cottage as creepy and said she and her husband never spoke to him.
Residents didn't connect Gerhartsreiter with the 1985 disappearance of the Sohus couple. He vanished soon after they did.
No trace of Linda Sohus has ever been found, but the bones of John Sohus were unearthed during excavation of a swimming pool at the San Marino property in 1994. With no clues, the mystery went cold again.
Across the country, a man variously known as Chris Crowe, Chip Smith and Clark Rockefeller was inventing new lives for himself.
This impostor wormed his way into high society and talked his way into important jobs. He married a wealthy woman and controlled her funds, but his identity unraveled when he kidnapped their daughter during a custody dispute.
His wife testified that he became increasingly paranoid when police begin inquiring about him.
When he was finally unmasked, he became the subject of magazine articles, true crime books and TV movies that sought to explore his bizarre story and get to the heart of the man behind the pseudonyms.
The resulting publicity led California authorities to revisit the Sohus disappearance. They realized the man in custody in Boston was not an heir to the Rockefeller fortune but was the man who had lived in San Marino decades ago.
Already serving time for the kidnapping of his young daughter in a Boston custody dispute, Gerhartsreiter was close to the end of his sentence and headed for freedom when he was charged with murder.
Defense attorneys suggested that Linda Sohus, not their client, killed her husband, but no evidence was provided to prove that theory.
And no motive for the killing was provided by prosecutors as they made their case against Gerhartsreiter.
It's unlikely that some details will ever be explained.
Gerhartsreiter chose not to testify in his own defense and much of the trial testimony came from people who only knew him long ago in San Marino as Chris Chichester, a stranger with a murky past.