Mark and Karen Duenas were teenage sweethearts. They were both raised as Mormons, married young, and started a family right away. They had five boys – Jason, Jacob, Tyler, Troy, and Casey. Mark was a driver for UPS. Karen was a full-time mother. When the boys were old enough, she taught part-time at Shasta College. Because he had to wake-up at 2am every day for his UPS job, Mark slept in a separate bedroom. He did so throughout their 33 years of marriage.
By 2010, Mark and Karen were in their early 50s. Their priorities shifted. Karen wanted to go back to school for nursing. Mark had initiated a long-distance affair (non-sexual) with an old friend, Annette Green, who lived in Idaho. In February 2012, Annette ended the relationship with Mark and wrote an apology letter to Karen. Three months later, Karen’s son Casey came home and found his father “freaking out.” Karen had been stabbed to death in her bedroom. Mark Duenas called 911. What he said on that call is up for debate. It was either “I killed my wife” or “I found my wife sick.” In jail, he told a friend, “I said whatever they said I said.” That didn’t please his attorney who is interviewed for the Dateline episode, A Killing In Cottonwood. It will air again on September 26 at 8pm on TLC.