Norma Hernandez says she told police in Camden, N.J., in the early 1980s that her brother had admitted to members of his church that he killed a boy in New York City in 1979.
"I went down to the police station and told them that my brother had killed and strangled a little boy," Norma Hernandez told ABC News.
She says she implored police to investigate but, "They never got back to me...I thought I'd at least hear back from a detective but nothing."
If convicted, Norma Hernandez said, her brother should spend the rest of his life in jail.
"As a sister you want to have compassion and you don't want to believe you don't want to believe that a sibling or someone related to you had did something like this," she said.
"As a human being I believe anybody is capable of doing it. All you need to do is lose your temper and you can do it. You can be a religious person and a person who's been good all your life and it only takes a couple of minutes for you to lose your temper and you're capable of going anything," she said.
Pedro Hernandez, 51, is a New Jersey resident, moving there after living in New York City in the 1970s where for a time as a teenager he worked as a bodega stock clerk. Last week he was charged with second degree murder in the 6-year-old's death following a sworn confession that he lured Patz into the bodega basement with the promise of a soda and proceeded to kill him 33 years ago.
Camden cops denied Norma Hernandez's claim that she asked that her brother be investigated some two decades ago.
"This is the first we are learning of Ms. Hernandez's comments," Camden Police Chief John Scott Thomson told ABC News. "Since this is an on-going homicide investigation, anything we do will be closely coordinated through the direction of the Camden County Prosecutor, Manhattan D.A., and the NYPD."
Hernandez was arrested last Thursday after a friend or family member recently contacted police and repeated his decades old church confession. Police said that person came forwards after the PAtz case again made headlines, when authorities reopened the investigation last month by excavating a basement apartment steps from where Patz went missing
Police Commissioner Ray Kelly said Hernandez had told relatives and friends as early as 1981 that he'd "done a bad thing and killed a child in New York."
Hernandez was arraigned last Friday from a New York City hospital, where he taken following his arrest and fears he might commit suicide.
His defense lawyer contends he is mentally ill and suffers from hallucinations. He did not enter a plea.
Norma Hernandez said she "had no idea" if her brother had a mental illness.
The search for Etan has been one of the largest, longest-lasting and most heart-wrenching hunts for a missing child in the country's recent history. His photo was among the first of a missing child to appear on a milk carton.
Stan Patz, Etan's father, reportedly spent Memorial Day on a bike ride through lower Manhattan, where he silently rode past 448 West Broadway, the address where Pedro Hernandez allegedly killed his son.