It was a surprising day in the retrial of the man accused of killing Etan Patz 37 years ago, as the brother-in-law of the defendant pleaded the Fifth Amendment, while his wife testified for the prosecution. NY1's Michael Scotto filed the following report.

Pedro Hernandez's sister Luz Santana said very little as she testified through an interpreter for two hours at Hernandez's murder trial Friday afternoon.

It was her first time in court. She was not a witness in Hernandez's first trial, which ended in a hung jury.

The prosecution contends that on March 25, 1979, Hernandez took Etan Patz to the basement of a bodega, strangled him and then threw his remains in the garbage.

At the time of Etan's disappearance, Hernandez lived with Santana in her SoHo apartment and worked at the bodega with her husband.

Under questioning by prosecutor Joel Seidmann, Luz said she did not know of any instances in which her brother heard voices or saw things that never occurred. She said, in fact, she never noticed anything unusual about her brother.

That could undermine a pillar of Hernandez's defense, which claims all of the four confessions by Hernandez were the result of hallucinations and his low IQ.

When asked if she and her brother had ever talked at the time about the missing boy, she said "no." She also responded "no" to a question about whether she had asked Hernandez if he had ever seen Etan. 

Luz's husband, Juan Santana, was expected to testify, but came in and pleaded the Fifth Amendment against self-incrimination. This after he learned that the prosecution told jurors during opening arguments that he might be hiding something. The jury will now here Juan Santana's testimony from the first trial instead.

Friday's testimony wrapped up the second week of the trial, which has been marked by some tense moments between the defense and prosecution.

Luz Santana is expected to return to the witness stand on Monday. It is unclear when her husband's testimony from the first trial will be read to the jury.