Dateline | April 03, 2014
>>> as time went by, margaret blare had come to accept michael peterson 's explanation of her sister's death years before. a tumble down the stairs in a germantown house.
>> i just believed what i was told. about the severe hemorrhage and presuming that a doctor had, you know, made this diagnosis.
>> and for close to two decades, the aunt from rhode island watched from afar as margaret and martha were raised by the petersons in germany and then in north carolina with michael's second wife kathleen . visits with the girls had been all too brief.
>> they would come visit me back and forth. but, you know, i just fell apart every time i had to send them back to north carolina .
>> but when she learned that kathleen had also been found dead at the bottom of the staircase, margaret began to fear her sister elizabeth 's accidental fall might be anything but.
>> whether i talked to her friends, i found out that blood had been dripping down the wall. well, that doesn't happen when you have a cerebral recommend wrath.
>> margaret recalled after elizabeth 's funeral there was one relative asking questions about michael peterson .
>> there was a member of my family who said i think michael peterson has something to do with liz's dpej.
>> said that very thought?
>> and at that time, i can remember saying people don't go around killing people. you know, that is absurd.
>> but now authorities in north carolina were starting to feel those grave suspicions might be warranted. after reviewing elizabeth ratliff 's case, investigators led in part by then durham assistant district attorney greta black concluded the only way they were going to figure out how elizabeth died was to dig up her grave.
>> we decided that it probably would be worth while to try to exhume her body to determine whether the findings in germany were accurate or not.
>> to do that, they had to get the okay from elizabeth 's daughters margaret and martha . the girls who believed in their father's innocence as fiercely as they mistrusted the authorities struggled with the decision.
>> the hardest thing i ever had to do was to write off on the exhumation of our birth mother .
>> but ultimately they agreed.
>> i signed off on it because we wanted to be like there is no way that this could have happened. like, please, look at the evidence. i will do this to free our dad of the accusations.
>> on a beautiful blue sky day, the remains of elizabeth ratliff were exhumed from the resting place in texas. her body was driven to north carolina where it would be studied by the same medical examiner who ruled kathleen peterson 's death a homicide.
>> there was a risk here.
>> you opened that coffin and found that authorities in german had been correct in ruling it a death by natural causes .
>> we decided it needed to be done.
>> rofl dice.
>> the detective looked through a morgue window as the top was pried off the coffin.
>> it was so airtight, it was hard to use the crank to get the casket to open once it was raised, you could see part of elizabeth ratliff 's face and hair. it was remarkable.
>> they were stunned. the body was practically intact.
>> her finger nail polish was still on. her dress was still perfectly in place.
>> she had her wedding dress on. that was very difficult.
>> the m.e. took a closer look at the injuries to elizabeth 's head. she was finding lacerations, deep gouges in the scalp, seven. seven lacerations?
>> it was amazing. it was uncanny. the lacerations were very similar to the ones that had been perpetrated upon kathleen peterson and in her findings, she made a decision that miss ratliff had been murdered. now pan dor why's box is open. who killed her?
>> the answer was obvious to the authorities. there were now two women in michael peterson 's life, both dead in a pool of blood at the bottom of the stairs. both believed bludgeoned. kathleen 's sister candace thought that peterson had killed both women.
>> i had a better chance of being struck by lightning than finding two people who i intimately know at the bottom of a staircase.
>> but to martha and margaret , the whole thing seemed absurd. the fact that michael was being accused of killing kathleen , the woman they called mom was bizarre enough. but now their birth mom, too? what would their father have gained by killing elizabeth ratliff ?
>> he would have gotten two screaming little kids out of it and that's it. like there is nothing -- there's no reason for it.
>> for the investigators in north carolina though, the death in germany became a strong building block in the circumstantial case for murder.
>> i'm just thinking that my case was getting a whole lot better.
>> and what's more, detectives learned that michael peterson had a secret life . secrets, lines were about to spill out in the durham courthouse. enter, brad the male escort .
>> what type of service did you perform?
>> oh, wow. that is pretty broad.