The last four years have been extremely rough for Patrick McStay, not knowing what happened to his son Joseph, daughter-in-law Summer and two young grandsons.
The family of four appears to have just vanished from their California home.
"Something in me said 'you're never going to see them again,' I just knew," McStay said.
The remains of Joseph and Summer McStay were discovered buried in a shallow grave about 80 miles outside of Los Angeles. The remains of two additional bodies have also been found. Those bodies have not been identified yet, but family members believe they are the couple's young sons, Gianni, 4, and Joseph Jr., 3.
The case is now a murder investigation and police have called the crime, "heinous."
Patrick McStay has lived in Texas for almost 40 years, he now lives in Spring. His son Joseph attended Dulles High School in Sugar Land before moving out to California.
McStay said he knew something was wrong when he hadn't heard from Joseph for a few days back in February 2010.
"I had been trying to contact them the whole weekend, I was very concerned."
Investigators reportedly found no signs of a struggle inside the couple's home, their SUV was found in a parking lot not far from the Mexico border and investigators discovered a surveillance photo taken from a border crossing security camera that shows shadowy images of a family walking and holding hands. The photo was snapped from behind, in the dark.
Some people speculated that the family just up and left but McStay said he knew better. His daughter-in-law would never cross the border with her boys, especially not on foot at night.
"You would have had to have dragged her kicking and screaming across that border."
McStay has been critical of the way investigators handled some of the details of the case and he has his own suspicions on a possible suspect.
"You have to be a cold blooded killer to murder two children," he said. "I think somebody hired somebody to do this - that's where all the evidence I have leads me. I just want whoever did it to be found and prosecuted."