The ex-wife of Pedro Hernandez will testify that she found a cutout picture of missing 6-year-old Etan Patz in a box of personal keepsakes years after the 1979 disappearance, a prosecutor revealed Friday during opening arguments in Hernandez's murder trial.

"She asked him about it," prosecutor Joan Illuzzi-Orbon told jurors in Manhattan Supreme Court. "He responded with anger and said she shouldn't be going through his private things."

Defense lawyers contend Hernandez's first wife is unreliable and has an ax to grind.

If the testimony is true it would be the first physical piece of evidence linking Hernandez to Etan between 1979 and his arrest in 2012.

Hernandez, 53, a married father from Maple Shade, N.J., is charged with murder and kidnapping in the notorious and long-unsolved case of Etan, who disappeared on May 25, 1979, while walking to catch a school bus in the SoHo neighborhood where he grew up.

Prosecutors have no known physical evidence, and are relying on a 2012 confession in which Hernandez said that while he was a teen working at a bodega near the bus stop he lured Etan into the basement by offering a soda and strangled him.

Illuzzi-Orbon told jurors that Hernandez had made general references to killing a boy on three occasions to a prayer group, his ex-wife and a friend before his confession, and -- although he never disclosed a motive -- told the jury he probably sexually molested Etan.

But the prosecutor spent much of her opening describing the Patz family's tragedy in a bid for sympathy.

She described Etan Patz as a "little guy with a big heart" who was allowed to go to the bus stop on his own for the first time because he was begging to be treated like a big boy, and left for the bus with a tote bag of matchbox cars and a $1 to buy a snack at the bodega.

"It was the mecca of candy and gum, and the biggest treat of all -- a soda," she said. "It was at this bodega where Etan was to meet his murderer ... didn't know that evil can greet you with a smile."

The prosecutor said Patz's mother Julie will testify about how she felt after making the decision to let her son go alone when he disappeared forever, but warned jurors that after her testimony she will not be seen in the courtroom.

"She has had to pull herself out of the darkest place," Illuzzi-Orbon said. "She can't sit and hear what this man did to her child."

Defense lawyer Harvey Fishbein argued Hernandez's confession was suspect because he has a borderline IQ that made him vulnerable to a high-pressure police interrogation, and suffers from a mental disorder that made him fantasize a crime he didn't commit.

He pointed out that a massive police search -- including four searches of the bodega basement -- turned up no evidence of a crime, or the bookbag that Hernandez would later say he discarded behind a refrigerator.

"There is not evidence," he said. "There's the words and the story as told by Pedro Hernandez. That's what this case is about."

Fishbein also told the jurors about the case prosecutors had once built against another man -- Jose Ramos, a convicted pedophile who dated Etan's baby-sitter and once told a prosecutor he was 90 percent sure he picked up Etan on the day of the disappearance.

Ramos was never prosecuted. The case against Hernandez, Fishbein said, "is just another sad twist in this tragic saga."