Everyone in the city had seen her face — yet for more than two decades, no one knew her name.

The anonymous child, dubbed “Baby Hope” by NYPD detectives, became the subject of a haunting police sketch after her emaciated, naked and battered body was found stuffed in a dirty cooler along with soda cans off the Henry Hudson Parkway in Manhattan in the summer of 1991.

The case shook Gotham to its core and remained unsolved till a stunning breakthrough 22 years later — a fascinating story that is now the subject of the latest installment of the true-crime TV series “TORN FROM THE HEADLINES: NEW YORK POST REPORTS,” which airs at 10 p.m. ET on Monday on the Investigation Discovery channel.

When the child’s body was discovered, even the most hardened city cops couldn’t help being touched by the atrocity of it all. Police Department detectives arranged a proper burial for the murder victim in a Bronx cemetery, erecting a head stone with “Baby Hope’’ etched on it. One of their wives bought a white dress for the little girl to wear in her coffin.

But the years frustratingly came and went without a break in the case.

Then in October 2013, as The Post exclusively reported, a tipster had seen a flier about the case that the cops had re-released on the anniversary of the discovery of Baby Hope’s body — and came forward to say she heard the girl’s sister talk about the child.

“Baby Hope” would soon have a name: Anjelica Castillo.

Anjelica’s sister, now in her 20s, told cops she remembered traveling to Mexico with her father years ago, while her mother and Angelica stayed behind.

Detectives tracked down Angelica’s mom to Washington Heights, where they used a ruse to get her to lick an envelope to get a sample of her DNA to test it against Angelica’s.

It was a match.

The mom claimed to investigators that her then-4-year-old daughter disappeared with her husband in 1991 and that she didn’t go to cops because her spouse was abusive.

But investigators learned that the little girl had been dumped on Queens relatives  — including her cousin, Conrado Juarez, a sick 52-year-old Greenwich Village restaurant dishwasher who eventually confessed to trying to rape the little girl and then smothering her when she attempted to scream. Juarez said he stuffed the child’s body in the cooler and tossed it off the side of the highway.

Another of Anjelica’s sisters later told The Post that the sketch of her tragic sibling was the spitting image of herself as a child.

“I wish I would have gotten the chance to meet her,’’ said the sister, Laurencita “Lorena” Ramirez, 27.

In an emotional ceremony at St. Raymond’s Cemetery in The Bronx in November 2013, an inscription was etched under “Baby Hope’’ on the child’s headstone: “Identified in 2013 as Anjelica Castillo.’’

But the solving of the case didn’t bring much joy to former lead Detective Jerry Giorgio, who had retired before it was closed.

“She was better off dead, I’m sorry to say,’’ he told The Post, noting the tortured life that Angelica had lived in her four short years on Earth.

Juarez ended up becoming sick and dying in jail in November 2018 while awaiting trial, a police source told The Post at the time.