Two years ago, Joseph and Summer McStay and their two sons, Gianni and Joseph Jr., vanished without a trace.
Home videos paint any idyllic portrait of a happy, all-American family who had just moved into a lovely home just outside San Diego in Fallbrook, California.
They were in the middle of remodeling the house when they disappeared. And even more puzzling—they left behind their two beloved dogs, Bear and Digger, as well as nearly $100,000 in savings.
Lisa Guerrero, INSIDE EDITION's Investigative Correspondent, was given exclusive access inside the McStay's home, which now sits empty of all furniture.
"This is our first look inside the Mcstay's home since they disappeared two years ago," said Guerrero, who toured the home.
"And this is where one of the last home videos of the McStays was shot. Just a beautiful, average American family enjoying their new home," commented Guerrero while in the McStay's kitchen.
Police found no sign of a struggle or foul play. But intriguingly, they did discover a search on the family's home computer for documents needed to travel to Mexico.
So what happened to the McStays after they pulled out their driveway two years ago? Were they kidnapped, victims of foul play, or did they just leave everything behind to start a new life in Mexico?
"It's still a mystery to me," said Detective Dave Martinez of the San Diego County Sheriff's Office. Martinez has helped chase down hundreds of leads but is still left grasping for answers.
"Do you personally believe they are in Mexico?" Guerrero asked.
"I can't rule it out. Is there a possibility they may be in Mexico? Absolutely," answered Martinez.
Another clue supporting the theory that the family headed south of the border is grainy surveillance video, which shows what many believe to be the parents leading their boys by the hand as they crossed into Tijuana on February 8th, 2010—four days after they first left home.
Interestingly, the woman in the video believed to be Summer is wearing Uggs, one of Summer's favorite shoes. Another pair of Uggs was left lying on the McStay's doorstep after they disappeared. And the family's SUV was found in a parking lot just blocks from the border crossing the very night the surveillance video was taken.
"I want to believe that's my brother in the video," said Joseph's brother Mike McStay.
Mike refuses to give up the search for his missing loved ones.
"It just makes no sense. I'm looking for a family of four. I don't want to have four grave sites," said Mike McStay.
Yet given the violent drug wars afflicting Mexico, Mike admits he doesn't believe the McStays would voluntarily take the kids there, especially since neither parent is fluent in Spanish and Summer's passport was expired.
"The not knowing is what's really wearing on everyone. Emotionally it's hard to bear that you can't resolve this. I have to keep hoping. Someone out there knows something. Someone has the key to this puzzle," Mike continued.
Guerrero and the I-SQUAD followed the trail of the McStay's south of the border, where sightings continue to be reported at hotels and restaurants across Mexico.
The search took them into the Yucatan Peninsula and the gritty coastal town of Progreso, near where the McStays were reportedly spotted in 2010.
"Joey McStay loved to surf, which is why many people believe he may be hiding out in a beach community," explained Guerrero as she drove into town.
Guerrero scoured the streets asking the locals if they recognized the family's picture, but no one seemed to remember the McStays.
Then they caught a break. Guerrero got wind of a possible McStay sighting not far from Progreso in the city of Merida, where she found American missionary Tessa Yeater.
Guerrero said, "Tessa, I'm going to ask you something really important. Do you recognize this family?"
"Yes. This is the family I saw in 2010 at the Walmart," said Yeater.
"How sure are you?" asked Guerrero.
"I truly believe with all my heart that the family I saw that day is the McStay family," said Yaeter.
Yeater says she saw the McStays shopping in the Walmart produce section. Yeater also says the family looked healthy and content - the only noticeable difference was that Joseph had shaved his head.
But the trail grows cold at the Walmart. And where the McStays went next remains a mystery.
"I'm hoping, with hope beyond hope that there is a happy ending to this story," said Mike McStay, who is pleading for anyone that may have spotted his missing family members to come forward.
For more information on the case please visit the McStay family website (below) or contact the San Diego County Sheriff's Office.
For more information go to mcstayfamily.org.