John and Wanda Casias was originally from Amarillo, Texas, but relatives said they moved to an area outside the city of Monterrey in the late 1970s or early 1980s and made it their home
Valerie Alirez, the eldest child of John Casias, told The Associated Press from her home in Greeley, Colorado, that one of her brothers found her father and stepmother on Tuesday dead in their home in Santiago, Nuevo Leon.
John Casias was a Baptist preacher and the couple ran the First Fundamentalist Independent Baptist Church in Santiago, Alirez said.
Her brother, Shawn Casias, who lives in Monterrey, said he went to his parents' home around 4 p.m. Tuesday to pick up a trailer. After he had hooked up the trailer outside he went into the home to say goodbye. He said he found Wanda Casias lying on the floor with an electrical cord around her neck and a gash from a blunt object on her head.
Missing from the house were a couple of computers, a plasma television and a safe that had been chiseled out of the wall.
The couple's Chevrolet Suburban was also missing, and Casias said he initially thought his father had been kidnapped.
But about four or five hours later, he said, a forensic investigator informed him that his father's body had been found in a storage room of a small building on the property. His father also had an electrical cord around his neck.
Fighting between the Zetas and Gulf drug cartels has brought a surge of violence and other crimes to Monterrey and the surrounding region since 2010. In poorer suburbs, entire blocks have been held up by gunmen and young people snatched off the streets.
Casias said a sister-in-law in Dallas had spoken to their mother around 11 a.m. Tuesday and everything was fine. So he believes there was about a five-hour window when the killings could have occurred before he showed up.
He said the killers did not take everything they could have, leaving two of the three TV sets. He said perhaps they were warned that he was coming, because anyone watching the winding road approaching the home could have alerted them.
"They're scum. They're not sophisticated," he said.
Speaking from his parents' home, Casias said the house was burglarized two years ago when the couple were on one of their periodic visits to the United States to talk at churches about their work in Mexico.
"We're convinced that it's somebody he knew," Casias said of the killers. He said authorities had some leads based on people seen around the home.
John Casias was 76. He had recently priced a knee replacement because he couldn't walk more than 100 yards (100 meters) without having to sit down, Shawn Casias said. Wanda Casias was 67.
Casias said his parents held services and prayer meetings at a church about 3 miles (5 kilometers) from their home.
The couple maintained a website, http://www.casias.org , with details of their lives and their missionary work
"The only hope for the Mexican people today is Jesus in them, the HOPE of glory," they wrote in one dispatch from last summer. "I confess that it's getting easier to witness to the wealthy, at least they are listening. The wealthy are fleeing to Canada and the USA for protection. The only problem is that when they return to re-new their visas the cartel is waiting, and either kill them of (sic) kidnap them for thousands of dollars, in some cases millions. The cartel has NO mercy or value for life. They are ruthless murderers!"
It was the second slaying involving American missionaries in a year in the Mexican region bordering Texas.
In January 2011, a Texas couple who had been doing missionary work in Mexico for three decades were attacked at an illegal roadblock in one of the country's most violent areas.
Nancy Davis, 59, was fatally shot in the head while her husband, Sam, sped away from suspected drug cartel gunmen who may have wanted to steal their pickup truck, authorities said.
The Davises were driving along the two-lane road that connects the city of San Fernando with the border city of Reynosa in the state of Tamaulipas, which borders Nuevo Leon.
Associated Press writer Katherine Corcoran reported this story in Mexico City and Christopher Sherman reported from McAllen, Texas.