What I thought made no sense.... **spoilers**
How they could have suspected the husband when none of the security cameras showed his vehicle at the scene. It seemed like a forced storyline to try and increase suspense, but it made no sense.
Also, the last time we see Leanne, she's already purchased flowers and is ready to cross the road back to her car and per my memory she looks happy...correct me if I'm wrong on that. So, when did she have this argument...seems it would have happened while she was buying the flowers and, therefore, she would not have looked so happy as she prepares to cross the road.
I guess grandpa must have a big guilt complex...his granddaughter is killed because he smokes cigarettes.