He’s their “Superman.”

A retired NYPD detective was hailed as a hero in a Brooklyn courtroom Wednesday for never giving up on his first ­homicide case, as the killer was finally sentenced for the crime.

The corpse of Lamethia ­McCollum — a pregnant mom shot the head in the bedroom of her Flatlands apartment in 2003 — had been discovered by her 8-year-old daughter, Victoria, who would tell her grandmother, “I don’t think my mommy is feeling very well.”

“I had a picture of the victim with her 8-year-old daughter on my desk, under my blotter,” ­remembered retired Detective Richard Lyman, who has been haunted by the mom and her little girl since the slaying.

“I’d work on other murder cases but keep thinking back about this one,” Lyman told The Post after the sentencing of Jefferson Jones, 42, the father of McCollum’s unborn child. Jones will serve 17 years to life.

“Come here, Superman!” family members shouted to Lyman in court. “This is a real hero!”

It was the first murder he “caught,” Lyman recalled.

“Hopefully it brings them a little closure,” he said.

Jones was the prime suspect from the beginning, “but we didn’t have enough to present at trial,” Lyman said.

But in 2012, Jones was busted for a Queens home invasion.

He had a Glock 9 mm on him; the lab called Lyman to tell him it was the same gun used in ­McCollum’s murder.

“That was the big break . . . that he held onto his weapon. My homicide matched up.”

Lyman drove to interview Jones at the Ogdensburg penitentiary upstate.

“The first words out of my mouth were, ‘Do you remember me?’ ”

“He said, ‘You look like that detective from Brooklyn.’ I said, ‘Yes,’ ” Lyman said with a laugh.

“I go, ‘We’re here to speak to you in regards to Lamethia ­McCollum.’ And he goes, ‘I don’t know who that is,’ with a straight face.

“Lamethia, the mother of your unborn child?” the detective repeated. “I don’t know who that is,” he replied.

Victoria, now 21, lives in Georgia and was not in court.

“I wish Victoria all the best in life,’’ Lyman said. “I wish all the best for that young lady.”

Additional reporting by Laura Italiano