Video: Family of Patz murder suspect offers insight

>>> back in this country, there are in questions tonight about the man accused of murder in one of the most infamous cold cases of our time. if pedro hernandez really did call etan patz , will his reported confession be enough to convict him? also tonight, two of hernandez ' sisters are speaking out. we get the story from michelle franzen .

>> reporter: the police never considered him a suspect until pedro hernandez confessed this week to killing etan patz in 1979 . back then, he was 18 years old working as a stock boy in a neighborhood store. a twist for those who have closely followed the case, includingly sa cohen, who wrote a book about the story.

>> this is something nobody saw coming. nobody had a clue.

>> reporter: but his family is offering some insikt. hernandez moved from new jersey shortly after etan disappeared. his sister says he began telling other relatives he killed a little boy and she noticed changes in his behavior, saying he was ablgting very strange, his stomach was always upset. another sister who asked for her identity to be concealed and voice altered, told a station in philadelphia, she can't imagine her brother killing anyone, but offered a message for the family.

>> so sorry by brother did that if he did.

>> reporter: his lawyer claims his client has a history of mental health issues. experts say investigators will need to build a case.

>> we don't seem to have any physical evidence , anything that links him to the crime and crime scene other than his proximity at the time that etan went missing.

>> reporter: back then, detectives like william butler worked tirelessly on the case going door to door . three decades later, investigators are back in the neighborhood searching for evidence again. today, there are flowers in a makeshift memorial in front of the building where the suspect says he killed etan . the memory of a little boy once again capturing the attention and hearts of people here and throughout the country. michelle franzen , nbc news, new york.

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