John and Wanda Casias knew the risks of being missionaries in one of Mexico's most violent, cartel-dominated regions, their children say, but they refused to curtail their work and instead put their ministry ahead of their safety.
The couple's slaying this week during a home invasion comes as missionary groups are rethinking how they prepare their volunteers to live in Mexico and other hotspots — or whether to send them at all.
The cartel-fueled violence in Mexico has made parts of the country so dangerous that the U.S. government warns Americans not to travel in those areas. Mission groups, which have long flourished in the border region and other areas, have been forced to dial back outreach efforts and some have cancelled trips altogether out of fear missionaries could be targets.
For those determined to work despite the risks, at least some groups are starting to send volunteers to the same security training camps corporations and aid groups have used for years to prepare their employees for risky overseas assignments.
"For all of our new missionaries in recent years it is mandatory that they get security training commensurate with the risk level in that country," said John David Smith, executive director of the Baptist Missionary Association of America Department of Mission, which has four families currently volunteering in Mexico according to its website. His organization also has put in place other safety measures such as forbidding missionaries from driving in and out of Mexico, which would force them to travel through more dangerous border areas.
The Casiases, who were from Texas but lived in northern Mexico for 29 years, were found Tuesday by one of their sons at their home in Santiago, Nuevo Leon, both strangled. Mexican investigators have said they suspect they knew their attacker because no doors or locks were forced.
Another son, John Casias, said he had spoken to them many times about their safety, but they lived by faith.
"They weren't ignorant," he said. "He (John Casias) knew about the murders. My mother knew about what was going on in Mexico. They understood it. They knew it. Were they scared to death? No. They weren't going to live in fear."
Their deaths came about one year after another missionary from Texas was killed in Mexico. Sam and Nancy Davis were driving out of Mexico in January 2011 when gunmen tried to stop their truck about 70 miles (112 kilometers) south of Reynosa. When they refused to stop, the gunmen fired, killing Nancy Davis. The Davises, too, had done missionary work in Mexico for three decades.
Sam Davis has since gone into hiding, his mother, Francille Davis, said Thursday.
"They're still wanting to kill him," she said of the gunmen. Davis, who lives in South Texas, said she did not know where her son was, but did not think he had returned to Mexico as a missionary.
It's unclear how many Americans are missionaries in Mexico. No single agency tracks the missions, which establish churches and schools, build homes, run feeding and counseling centers and perform other outreach. There has been no evidence that the Casiases were targeted by a cartel, and authorities believe the Davises were likely attacked for their truck. Generally, missionaries say they try to keep a low profile and go about their work.
David Dose, who runs Fort Sherman Academy, a security training firm in Idaho that specializes in faith-based clientele, said his training has increased 400 percent in the past five years. While faith-based groups were slower to seek such training than corporations, he said he's seen a change in the past couple of years as groups look for more ways to prepare than faith alone.
"They're already spending all the time and money they can just to prepare for what they're doing and volunteering," Dose said. "But also there's been a bit of a struggle between at what point is it just not in the same spirit."
The academy's training generally covers areas such as information security, risk assessment and minimization, as well as specific situations such as hostage taking. He said while aid groups in some hostile countries hire private, armed security guards, the faith-based groups he works with do not.
"There's no desire to take an arsenal and go protect yourself in that way," Dose said of his faith-based clientele. "We're having to deal with how people can use their brains and the thinking that God gave them to try to improve the situation. But in the end ... you have to assume there's probably some risks you have to live with because you believe in what you're doing."
Many organizations have seen the number of missions they send to Mexico decline.
Daniel Rangel, director of River Ministry/Mexico Missions, which is part of the Baptist General Convention of Texas, said he only had about 80 mission groups last year compared to 400 before the violence got out of hand. Most that do come stay on the U.S. side of the border and just cross during the day and return later, he said.
The reduction in missions has been difficult for their partners in Mexico. "A lot of the people on the border feel abandoned," he said. They still ask churches to send resources even if they can't send volunteers.
For years, Jim Walters, director of Vision Ministries in Indiana, brought mission teams to Saltillo in northern Mexico. They would fly into San Antonio, rent vans and drive into Mexico through Laredo.
But a few years ago they stopped going.
"I was becoming increasingly uncomfortable with the safety and security issues," Walters said. "People were more reluctant to go."
Before making his decision to stop the trips, Walters said he spoke with many other groups doing similar work.
"I sensed a lot of them had discontinued or were seriously considering," he said. "It's a shame. A lot of good work and resources have dried up for them."
They now take their missions to Barbados.
ABC News on the Casias deaths: