TODAY | May 21, 2012
>>> we're back now at 8:10 with a story that generated a huge response here on "today." two extraordinary families brought together by a deadly accident and a dramatic case of mistaken identity. matt caught up with them for "dateline's" 20th anniversary special.
>> reporter: some stories stay with you forever.
>> how are you?
>> reporter: this is one of mine. it involves a young woman .
>> ah! her family.
>> nice to see you. and another family. equally remarkable. it all started six years ago. with a high-speed collision between a semi truck and a van filled with college students and staff. soon, colleen and newell cerak got a call about their daughter whitney .
>> i think they just told me that she had died. i just thought oh, so sad. i just said thank you. i didn't talk very long on the phone.
>> reporter: the crash killed five people. others survived. some with serious injuries. laura van ryn 's family rushed to the hospital to find her covered with bandages. how hard was it to see, suzy, to see your daughter in that state?
>> horrible. very.
>> it was very hard.
>> very hard.
>> reporter: the ran vivan ryn's set up a bedside vigil for their daughter laura . while the cerak's planned a funeral for their daughter whitney . but in the hospital as the days went by, something strange was hopping.
>> you noticed something about her teeth.
>> these two on either side in the front looked different to me.
>> reporter: and as the patient in the bed began to regain her appearance, and her memory, the van ryns doubts increased. after five weeks of round-the-clock care they asked a question of the woman they still hoped was laura .
>> i said can you tell me your name? and she said, " whitney ."
>> reporter: a shocking realization. somehow in the chaos of the crash, two women, both young, blonde, and pretty, had been misidentified.
>> immediately realization that, you know, our daughter had died in the accident.
>> that sounds hard.
>> well, it was hard. but we knew where our daughter was. and we knew that newell and colleen needed to know where their daughter was.
>> reporter: one family's devastating loss meant another family could be whole. within hours, the ceraks were reunited with her daughter.
>> did she say anything?
>> she was like shaking her head, yes, like yes, it's whitney .
>> reporter: so this is your room?
>> reporter: whitney recovered fully thanks in part to the devotion of a family that wasn't even her own.
>> i love the van ryn family. they're so great.
>> reporter: you look fantastic. and what's new with whitney ? well, just about everything. tell me about the last few years.
>> i don't even know where to start.
>> reporter: let's start with her boyfriend matt. in the same church where whitney 's family once held her funeral, she and matt got married. colleen and newell , you never thought you were going to see that wedding day.
>> it was really a special day.
>> it was such an unbelievable moment for us, because we were at a moment in our life when we thought this would never be a possibility.
>> reporter: and just four weeks ago, the biggest news yet. oh, my goodness, whitney , he's adorable. but whitney and her family face another big challenge. and soon. matt is in the army. and in about two weeks, he's shipping off to afghanistan.
>> this will be like a whole different level of hard.
>> reporter: but somehow you know she'll get through it. just as these two families came through an almost unimaginable ordeal. their love and their faith unshakable.
>> we are just glad that we've been a part of it and god has given us the strength to get through it.
>> for more of matt's stories and others i hope you'll join me as i host "dateline's" 20th anniversary special tomorrow night at 10:00 , 9:00 central time right here on nbc.