who until mid-trial had refused to say one word in public, the woman at the center of it all, linda opdycke-- miss opdycke, raise your right hand. keith morrison: --whose long silence was about to end. coming up, and end it would, with a bang, with stories of who she said was the real mark stover. and he had a pistol in his hand and laid it on the pillow next to my head. i see mark on a hillside behind my house. he's looking through the scope, pointing the rifle at me. keith morrison: when "dateline" continues. happiness is powerful flea and tick protection from nexgard. nexgard kills fleas and ticks all month long. and it comes in an easy-to-give tasty chew. and that makes dogs and owners happy. no wonder vets love it too.