NEW YORK (AP) — Jurors deliberating a verdict in the 36-year-old missing-child case of Etan Patz said Tuesday they were deadlocked for a second time, but a judge told them to keep trying.

The jury sent a midday note saying it was still stuck after deliberating since April 15 in the case against Pedro Hernandez. He admitted killing Etan, one of the first missing children ever pictured on a milk carton, but his defense says the confession is false.

"After serious, significant and thorough deliberations, we still are still unable to reach a unanimous verdict," wrote the jury, which has reviewed dozens of exhibits, re-listened to hours of testimony and both sides' closing arguments, and even created a spreadsheet to organize the discussion.

The defense asked Tuesday for a mistrial, arguing that the deliberations had gone on long enough.

"This is a tired jury that says it can't reach a verdict, and we asked the judge to respect that," defense lawyer Harvey Fishbein said outside court.

Prosecutors, meanwhile, sought an instruction telling jurors to reconsider their views. State Supreme Court Justice Maxwell Wiley instead only asked them to keep deliberating, while reminding them they weren't required to reach a verdict.

Etan disappeared while walking to his school bus stop on May 25, 1979. The anniversary would become National Missing Children's Day after his case helped draw national attention to the cause of missing children.

Investigators dogged leads for decades before Hernandez — who had never been a suspect — told authorities in 2012 that he had choked Etan after offering a soda to lure the boy to the basement of a store where he worked. Hernandez, now 54, said he had put Etan's body in a box and walked it a few blocks away.

Etan's body has never been found.

Long before a tip led police to Hernandez' door in Maple Shade, New Jersey, he told some friends and relatives he'd killed a child in New York. His lawyers say all his confessions are imaginary, produced by mental illness. They also have pointed to a longtime suspect who was never charged.