Cozy Mystery : the Murder Mystery Plot

The main characters are Liz and her new hubby Roger. Right after their wedding, they get a call from friends Bob and Renee, who were at the reception. They came back to their rooms after the reception to find Renee's sister was murdered while watching their baby. Liz and Roger jump in to help figure out who did this. Can they figure this out before it's too late to save themselves?