A Family Vanished — Then Came Desert Graves and a Sledgehammer. The Mystery Led to Someone Close to Dad

Joseph McStay and his wife Summer, along with their 4-year-old son Gianni and 3-year-old son Joseph Jr., disappeared in 2010 — four months after they moved into their two-story home in the San Diego suburb of Fallbrook, Calif.

Left unattended at the home were the family’s two beloved dogs Bear and Digger.

Authorities also found rotting food on the kitchen counter and clothes tossed on the floor, though there was no sign of forced entry. Additionally, nearly $100,000 remained untouched in bank accounts belonging to 40-year-old Joseph, who ran a successful decorative-fountain business.

Their disappearance made national news when the family’s white Isuzu Trooper was found at a strip mall near the border — leading police to wonder if the family of four chose to move to Mexico and start a new life.

However, a gruesome discovery years later changed all that.

In 2013, a motorcyclist came across a skull in the Mojave Desert near Victorville, Calif., and contacted investigators who then uncovered the family buried in two shallow desert graves.

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It was determined the family had been viciously beaten to death with a sledgehammer that was found in one of the graves.

A year later, prosecutors charged Charles “Chase” Merritt — Joseph’s onetime business partner — with murder, alleging that he was in debt and had a gambling problem when he killed the family of four for financial gain, PEOPLE previously reported.

During his trial, prosecutors alleged that Merritt carried out the killings after McStay decided not to work with him anymore, per NBC News.

McStay allegedly had told friends that Merritt was stealing from him, prosecutors said, according to the outlet.

Merritt was convicted of the killings and later sentenced to death in 2020. At his sentencing, he maintained his innocence and denied murdering the McStay family.

“I loved Joseph,” he said, per NBC News. “He was a big part of my life and my family’s life. I would never have hurt him in any way. I would have never raised my hand for a woman or child. I did not do this thing.”

McStay’s mother, Susan Blake, called the former welder “a despicable monster.”

“How could you beat two precious little babies? How scared were they, Chase? Crying for Mommy and Daddy? Chase, you are a low life baby killer,” Blake said at sentencing, per the outlet.

The murder of the McStay family is the subject of a new two-hour ABC 20/20 episode airing Friday, Oct. 3, at 9 p.m. EST.