The killer of Etan Patz, the first missing child on a milk carton, has been sentenced.

Two months on from being found guilty of the murder of six-year-old Etan Patz – the first missing person to appear on a milk carton in the US – convicted killer Pedro Hernandez has been sentenced to 25 years in prison.

“Now I know what the face of evil looks like and he’s finally convicted,” Etan’s father Stan Patz said while staring down Hernandez inside the Manhattan Supreme Court on Tuesday.

“After all these years, we finally know what dark secret you have locked in your heart,” Stan continued.

Etan Patz disappeared from his native SoHo neighbourhood in New York nearly 38 years ago on the morning of May 25, 1979.

His mother, Julie Patz, was busy with Etan’s younger brother and another child who had stayed the night, and Etan’s older sister didn’t want to get out of bed. And so, the independent young boy begged to be allowed to walk the two blocks to the school bus stop on his own for the first time.

Julie reluctantly agreed and hours later, when Etan failed to return home later that day, she learned her son had never made his way to school.

Decades of false leads and uncertainty followed the family, with Etan’s face being plastered across milk cartons, but finally, in 2012 police arrested a now 56-year-old Hernandez, who was 18 at the time of Patz’s disappearance and worked at a bodega nearby.

Hernandez claims he lured Patz into the store with the promise of soda before choking him to death. Tragically, Etan’s body was never recovered, but it is understood Hernandez dumped the corpse into the garbage, something Stan Patz alluded to in court.

“You took our precious child and threw him in the garbage,” Patz said, adding, “I will never forgive you. The god you pray to will never forgive you. You are the monster in your nightmares.”

According to Daily News, prior to his sentencing, presiding judge Justice Maxwell Wiley deemed that irrespective of Hernandez’s low IQ and mental health issues, “evidence was presented showing he maintained a parental relationship with at least one of his children so he is certainly in a position to know not just what he did to Etan Patz, but what he has done to the people who love Etan.”

Following his statement, Wiley served Hernandez 25 years in prison – the maximum sentence available for his crime.