Charles "Chase" Merritt, left, reacts in court after being found guilty of four counts of first-degree murder of the McStay family.
The case captivated America: The family, Joseph and Summer McStay and their two sons, 3 and 4 years old, disappeared abruptly from their Fallbrook, California, home in 2010, bowls of popcorn left uneaten and no signs of forced entry.
A man accused of killing a California couple and their two children and burying them in the Mojave Desert has been found guilty of first-degree murder.
With the conviction, the trial will enter a second phase for the jury to decide whether Merritt should receive life in prison without the possibility of parole or be executed.
A verdict was reached Friday by jurors, but it was not announced publicly until Monday. Merritt had been working on a book about the McStay family murders when he was taken into custody, CBS News reported at the time. Three years later, their bodies were found in shallow desert graves more than 160 kilometres away.
In 2013, their bodies were found in shallow graves in the desert after an off-road motorcyclist discovered skeletal remains in the area.More news: Yuvraj ready for fun after announcing global retirement
With the jury's guilty verdict in, Merritt could face the death penalty.
The disappearance of a USA couple and their two children puzzled California investigators for years.
Prosecutors say financial records show Merritt tried to loot the business bank accounts just before and after the family disappeared and backdated checks to February 4, knowing it was the last day anyone had contact with McStay.
Deputy District Attorney Britt Imes highlighted evidence he said pointed to Merritt: cellphone data, questionable activity in McStay's business account, gaps when Merritt was "off the grid" for hours on key dates, his DNA on McStay's steering wheel.
"It is one big piece of collective evidence", Imes told the jury.More news: Hackers Hit US Customs to Steal Travelers' Photos, License Images
Prosecutors argued that Merritt killed Mr McStay out of greed at a time when he owed him money and was being cut out of the business making and selling custom water fountains.
Nothing in the graves ties Merritt to the bodies, the defense argued.
The family vanished from their San Diego County home in 2010. Plus, he previously had been in the Trooper.
Merritt's attorney, James McGee, said he believed his client was wrongfully accused and prosecutors built the case based exclusively on motive.
The family's disappearance had puzzled investigators, who said there were no signs of struggle at their home.
The fatal beatings had been brutal.More news: Kevin Durant boards plane to travel with Warriors to Toronto