Decorated NYPD Det. Wendell Stradford has cracked more than 100 murder cases in his 37 years on the job and is now closing the book — on his career.

Stradford, 62, who spent the bulk of his career working cold cases, is retiring Wednesday.

“That was one of the things about being in cold case,” the Staten Island native told The Post this week. “I mean, you can’t solve them all, but the ones that you can solve give you satisfaction because you’re able to say to the family, ‘We got ’em.'”

A one-time recipient of the NYPD’s Combat Cross for heroism, Stradford said none of those cases stand out more than the 1988 rape and strangulation of 9-year-old Joi Little and her mother inside a Bronx apartment.

The girl’s grandmother was the one who found the bodies, he said.

It took 25 years, but he was finally able to make a case against Robert Fleming, who was convicted and sentenced to two consecutive 25-to-life sentences in 2013.

“There were several suspects initially,” he said. “You know, friends of the mother. The grandmother was adamant that she wouldn’t move from the building until the killer was caught. So, she was there from like ’88 until I finally arrested him.”

Stradford said cops were unable to find a DNA match linked to the brutal slayings until Fleming was arrested on a parole violation and his DNA was put into the system.

But the case still hit a snag when prosecutors felt that wasn’t enough.

So, the detectives went out and found two eyewitnesses who saw Fleming in the building — and ended up getting him to confess to the murders.

“He got what he deserved and it’s finally over,” Joi’s aunt, Wanda Cooper, said then.

Stradford said Joi’s father, who was at one point eyed in the case, “walked up and shook my hand and thanked me” when the case was solved.

There were other successes in the detective’s long career, including the 1996 torture and slaying of a Bronx couple in front of their young children in the family’s Williamsbridge home.

Esteban Martinez, 30, and Linda Leon, 27, were tortured with a sheetrock saw and shot to death on Dec. 15, 1996 — with the killers then debating where to kill the kids as well.

The children, ages 6, 5, and 3, were spared at the urging of two women who were among the killers.

“They shot them in the head,” Stradford recalled. “They wanted to kill the kids and the girls talked them out of it. ‘We gotta kill the kids. They’ve seen our faces.’ The girls said, ‘No, no, no.'”

It took until 2014, but Stradford says his squad tracked down and arrested Keisha Washington, Denise Henderson and Kevin Washington in Baltimore and all were later convicted in the brutal slayings.

Stradford also made the case against serial killer Rodney Alcala, the so-called “Dating Game Killer” sought for 1971 rape, torture and strangling of two Manhattan women.

Alcala got the moniker for his 1978 appearance on the popular TV game show.

“He would knock these women out, torture them, you know, knock them out again, wake them up, and he would assault them again,” Stradford said. “We got his dental impression and we matched it to the bite marks on one of our victim’s bodies.”

Alcala, who was by then jailed in California for similar murders, was extradited to New York in 2013 and convicted of the Manhattan crimes — getting a new 25-to-life term.

He died behind bars earlier this year.

“Wendell Stradford spent 37 years dedicated to bringing justice to crime victims across New York City,” DEA President Paul DiGiacomo said. “To say Wendell made a difference in the lives of New Yorkers is a complete understatement. His service didn’t stop there either as he took care of fellow detectives as a DEA delegate. A superb investigator, Wendell is known as a true gentleman on top of it all — by those in every rank on the Job and the people he so proudly served.”

After a long career chasing bad guys and solving heinous crimes, Stradford said he’s looking forward to slowing down and focusing on his growing family, when he’s not busy consulting on TV crime shows.

“I’m going to take it easy for a little bit and spend some time with my granddaughter and the new one coming,” said the longtime lawman, whose daughter is expecting.

“It’s bittersweet,” he said about finally retiring. “But I met a lot of good people along the way and we were able to give a lot of families closure by looking at a lot of cases they thought the police department had given up on.”