but it was clear there were still too many questions to take this case to court. the theory was that giselle had done something to bring about her demise. it just was a question of-- of what. yes-- of what and how we prove it. keith morrison: in fact, without a body, how could they prove there was a murder at all? lester holt: coming up-- in a strange twist of fate, the mother of amber dubois joins another search for michelle along with her new dog. she was barking. she jumps up on me and takes off again. and i followed her, and i noticed rope sticking out of the ground. lester holt: a dramatic discovery, when "dateline" continues. [music playing] what does life look like during your period? it's up to you, with tampax pearl. you get ultimate protection on your heaviest days and smooth removal for your lightest. tampax pearl and pearl active. for up-to 100% leak-free work outs.