he thought nobody was looking. >> chris hall ambushed his wife, grabbed her by the hair, slammed her head twice into the concrete edge. he's holding his wife of almost three decades under the water, showing absolutely no mercy, no remorse. an absolute desire to end her life at that point. >> and then the piece de resistance. >> he then gets out of the spa, walks into the house where his plan is to wake his 22-year-old daughter, who he can use as an alibi witness. >> one little quibble. why? in fact, as convinced as he was of hall's guilt, strunsky conceded the why was a problem. he didn't legally have to know, he said. but he just didn't. there it was. >> it's emotionally unsatisfying not to have that answer, not to know the entire narrative of what happened.