Mexico violence curtailing church missions  McALLEN, Texas --
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.