In “Motive for Murder,” Mankiewicz takes a deeper dive into the twisty tale of two Houston murders featured on a Friday-night  “Dateline” episode he anchored last November on NBC.

The first two “Motive for Murder” episodes, available Thursday, are already #1 on Apple’s podcast charts. A new episode will premiere each Thursday starting next week.

“The great thing about this case is that it didn’t fit the standard ‘Dateline’ template,” Mankiewicz tells The Post. “It wasn’t the husband, it wasn’t the wife, it wasn’t the boyfriend or girlfriend, it wasn’t for insurance … what made it such a compelling story to tell was just trying to figure out the motive, which had investigators scratching their heads for a really long time.

“There were theories that explained one victim’s murder but didn’t explain the other victim’s murder,” he says, “and the explanations just didn’t make sense.”

The young victims — Iranian activist/researcher Gelareh Bagherzade and Coty Beavers — were murdered 10 months apart in 2012. They knew each other, but connecting their slayings flummoxed investigators for six years.

“I really wanted to do this one, since it fell sort of outside the typical ‘Dateline’ footprint,” Mankiewicz says of the podcast, produced in conjunction with Neon Hum Media. “If you don’t know the story already, you’re not going to know who it was in the first five minutes. This was an opportunity to tell it in a different way and it’s also unusual just because the circumstances were so weird and it’s such a long, incredibly intricate case.

“A friend of mine, who’s a homicide detective, says all murders, when you’re looking for motive, classify them as love, money or pride.

“That was the original title of this podcast.”

Mankiewicz says that anchoring “Motive for Murder” provided him more flexibility than a typical “Dateline” episode in terms of storytelling.

“In in a two-hour ‘Dateline’ we’re going to leave stuff out,” he says. “Each hour is 38 minutes of actual programming. In a podcast, it doesn’t make any difference: if you can explain something well enough and clearly enough, you can put it in. For instance, if I’m talking about somebody sentenced for one crime but not another … that’s not something that’s going to get into a ‘Dateline’ episode, since it’s difficult to explain and would require me talking too long on TV.

“But our fans, people who listen to podcasts and watch ‘Dateline,’ will come up to me at the airport and say, ‘Why didn’t the Modesto cops use Luminol at the second crime scene?’ They want to know exactly what went into that [perpetrator’s] sentencing recommendation — so you can get those little granular details into the story and still keep it entertaining for everyone else.”