The last exit on Interstate 5 funnels drivers into a swirl of activity at the U.S.-Mexico border in San Ysidro. Mexican pop music blares from an open-air bazaar where Zapata T-shirts and $6.99 hip-hugger jeans are sold. Women headed back to Mexico drag shopping carts stuffed with bags from Kmart. Cabdrivers sit on a bridge overlooking the border and wait for customers. The sidewalks are jammed with people.
An advertising kiosk promotes its busy location to potential customers: 1.5 million eyes see this ad every year!
But no one has seen or heard from a San Diego County family of four whose 1996 Isuzu Trooper was found in a strip mall parking lot here Feb. 10 -- four days after Joseph McStay, his wife, Summer, and their two children, Gianni, 4, and Joseph, 3, disappeared.
Nearly three weeks after they vanished, no one has an explanation. Family and friends describe Joseph McStay, a 40-year-old businessman, and his 43-year-old wife as devoted parents excited by their recent move from San Clemente to a home they bought on a cul-de-sac in Fallbrook.
"They're a very happy, loving couple. They're very active with their children," said Blanche Aranda, Summer's mother. "How do four people vanish without a trace? Such a loving family -- who would want to hurt them?"
Authorities say they are stumped by the disappearance of a family that had no apparent financial or marital problems and no known enemies or connections to drugs or crime.
"It doesn't make sense," San Diego County Sheriff's Lt. Dennis Brugos said. "Usually something pops up early in these kinds of investigations. But this one remains a mystery. They seem to be a fairly typical family. I've never seen anything like it."
On Feb. 14, McStay's brother went to the family's home to check on them after Joseph's partner in a water fountain business said he couldn't reach him. Michael McStay found the couple's two dogs had been left unfed and perishable food was on the kitchen counter.
It's unknown why their vehicle was found at the border, authorities say.
Investigators are scouring surveillance video from the pedestrian crossing into Mexico and are working with Mexican police.
Fliers with the family's photo's have been distributed on both sides of the border.
But Brugos said there's no evidence the McStays crossed the border -- or even that they drove their SUV there.
The vehicle was locked and no evidence of a struggle was found, he said.
The couples' cellphones and credit cards have not been used. Aranda said her daughter's expired passport was found at home.
"We even checked to see if they were in the witness protection program," Brugos said.
The mystery has made compelling fodder for cable television talk shows.
The National Center for Missing & Exploited Children spotlighted the McStay case on its website and a volunteer missing persons support group, Texas EquuSearch, plans to search the surrounding area using a drone aircraft.
Meanwhile, the McStays have posted photos and videos of the missing family on YouTube, Facebook and are posting news updates at www.mcstayfamily.com.
"My gut feeling is telling me that they are being held against their will in some way," Michael McStay told CNN.
Multiple messages left for McStay for this story were not returned.
Friends and family say they are certain of one thing: Joseph and Summer McStay would not have taken their children to Mexico given that country's ongoing drug wars.
Diane Cirignani, a bridesmaid at the couple's 2007 wedding, the second for both, said she and her husband talked about joining the McStays on a vacation. They all agreed Mexico was out of the question.
"Especially when it came to taking the children," she said.
In recent months, the couple were busy renovating their new five-bedroom home with carpeting, paint and granite countertops.
"He was extremely excited about it," said Steven Kowalczyk, a mortgage broker who got to know Joseph when McStay rented an office next to his in San Clemente.
Kowalczyk said McStay moved out of the office and was working from his home in recent months.
Despite the recession, McStay seemed to always have new business for the interior water features he designed and manufactured.
"His cellphone was on 24 hours a day," Kowalczyk said. "He never missed a business call."
The silence now is deafening.
"Hopefully, with all this exposure, the pictures of them everywhere, it will trigger the memory of someone who has seen them," Aranda, Summer's mother, said.
"I'm just so happy," she added, "that the four of them are together. Wherever that is."