TIJUANA, Mexico (AP) - The slayings of four young Americans in Tijuana sowed fear in Southern California on Friday as Mexican prosecutors tried to determine whether the youths were involved in the country's violent drug trade or innocent victims of a brutal crime.
The victims, two men and two women in their teens and early 20s, said they were headed for a night of partying across the border only to be found strangled, stabbed and beaten a few days later.
Mexican officials are investigating whether any of the four San Diego-area victims had ties to the drug trade, after a toxicology report tested positive for cocaine on the body of Brianna Hernandez, who was either 18 or 19.
Another victim, Oscar Jorge Garcia, 23, was apprehended in the San Diego area in January 2008 with six illegal immigrants in the car, but never charged in the case, U.S. Immigration and Customs Enforcement spokeswoman Lauren Mack said.
The parents of 20-year-old victim Carmen Jimena Ramos Chavez on Friday described a vibrant Chula Vista High graduate who worked at an amusement park for children and planned to become a hair stylist.
"She was a happy girl, with a desire to explore the world," said her father, Rogelio Ramos Camano, of Chula Vista. "Young people are like that. They think nothing will happen. I was like that, too."
Mexican prosecutors said the victims had been bound and tortured - common tactics by Mexican drug gangs - before being left in a van in a dusty slum on the outskirts of Tijuana.
Jose Manuel Yepiz, a spokesman for the Baja California state prosecutor's office, said investigators were examining a threatening letter to one of the victims from a jail inmate in San Diego.
Prosecutors said they had ruled out the possibility that the killings were a case of drug gangs targeting tourists.
Tijuana, which sits across the border from San Diego, has a reputation as one of Mexico's most violent border cities. Authorities said 843 people were slain there in 2008, many in drug-related violence.
Since taking office in December 2006, President Felipe Calderon has sent more than 45,000 soldiers to combat drug cartels in the country whose turf battles have killed more than 10,750 people over the last two-and-a-half years.
Violence had diminished in Tijuana in recent months, only to pick up a few weeks ago with seven police officers killed in brazen attacks on one day.
Victor Clark, a professor at San Diego State University's Center for Latin American Studies, said criminal ties with any one of the Americans could have spelled disaster for the group.
"Maybe they broke the rules, which means death" when dealing with Mexico's drug cartels, said Clark, a Tijuana resident and native. "And they dragged their friends down with them."
Relatives said the victims were familiar with both sides of the border and navigating the area's bilingual culture - but may have taken their safety for granted.
Ramos said he had often told his daughter, who was born in Tijuana but raised from a young age in the U.S., that Tijuana was too dangerous, and she assured him she was always careful.
But Ramos said he didn't offer any warnings as his daughter got ready to go out with her friend Brianna on May 7, even as he watched a news program about killings in Tijuana on Mexican television.
"I think God put that out there so I would do something, but I didn't dare," he said in Spanish, shaking his head, recalling how they were already primped and ready to go.
U.S. tourists, already warned by the U.S. State Department to be cautious in Mexico because foreign bystanders have been killed, now appear even less likely to visit once-popular destinations like Tijuana.
"I'm not going to T.J. unless it's absolutely necessary," Amelia Lopez, a friend of a victim told television station San Diego 6. "Before, you know, you go to eat of have a good time or shopping. Nothing like that."
Associated Press Writer Solvej Schou contributed to this report from Los Angeles.
Copyright 2015 Associated Press. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.