A San Diego Sheriff's Office spokeswoman said the U.S. Border Patrol and Interpol, the International Criminal Police Organization, are aiding the investigation, which includes homicide detectives.
"It did not appear that this family was planning on going on a vacation, and the dogs were not being cared for," Lt. Dennis Brugos of the San Diego Sheriff's Office said in a previous interview.
"We've been strategizing to figure out where they might be," Brugos said. "We're working with border control to find out whether there is any activity on their passports, and whether they had any connection to narcotics or gangs, but it doesn't seem as though they do."
"It's an absolute mystery," he said.