Metro

Network’s correspondent probing Dave’s extortion scandal

There’s a civil war brewing at CBS over the David Letterman extortion scandal.

CBS News’ top investigative correspondent is digging for dirt about fellow Tiffany Network journalist Robert “Joe” Halderman, “Late Show” host David Letterman, whom Halderman is charged with blackmailing, and the woman at the center of their sordid love triangle.

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Halderman’s colleagues at “48 Hours” are furious that “CBS Evening News” correspondent Armen Keteyian and a special team are nosing around their operations for a story on the alleged shakedown of Letterman, whose show is the network’s most profitable, sources said.

Those “48 Hours” staffers are worried about being made to look guilty by association with Halderman — a longtime producer at the news magazine — and are questioning the benefit of the “Evening News” probing people and entities in the CBS family.

Among those people is Halderman’s ex-girlfriend — “Late Show” staffer Stephanie Birkitt — a 34-year-old who carried on an affair with Letterman even while living with the producer, and who herself previously worked for “48 Hours.” Birkitt’s alleged cheating, sources said, spurred Halderman to extort $2 million from Letterman, 62, by threatening to expose the affair.

“How is this good?” asked a “48 Hours” source about the “Evening News” probe.

But an “Evening News” source said the probe was spurred by a desire to avoid sitting on the sidelines while other media feast on the scandal.

“CBS cannot be seen to be burying its head in the sand,” the source said.

Keteyian — who in the week since getting the assignment has conducted several background interviews in the news department — has known Halderman for years.

Letterman is likely not happy about being the focus of the CBS News eye, particularly since his admitted philandering with female “Late Show” employees has fueled the media firestorm.

A spokesman for Worldwide Pants, the Letterman-controlled company that produces the “Late Show,” said, “We have not been contacted by CBS News, but we would hope that any reporting on this matter focuses appropriately on the alleged felony extortion attempt on David Letterman.”

Halderman’s defense lawyer, Gerald Shargel, hasn’t been contacted by CBS News with any requests for interviews with either him or Halderman. But even if CBS News makes such a request, “I don’t have clients discuss the case with anyone prior to trial,” Shargel said.

A “CBS Evening News” spokesman refused to comment yesterday.

dan.mangan@nypost.com