He brought her up from coffee-fetcher to personal assistant to on-air personality — and then she inadvertently brought him down.
The woman at the center of David Letterman’s stunning late night mea culpa is his former assistant, Stephanie Birkitt, a vivacious 34-year-old highlighted blonde who started out as an intern, became his assistant — and then his office paramour, sources said yesterday.
In a bombshell on-air confession Thursday, Letterman, 62, admitted to having bedded a number of his female staffers over the years.
He told his audience about the flings while explaining how he was being shaken down by a longtime “48 Hours” producer, Joe Halderman, 57, who allegedly told the late night lothario he was going to expose his affairs, including the one with Birkitt.
Halderman was until recently living with Birkitt, whom he’d been dating for several years.
Birkitt and Letterman’s heated sexual relationship began in the midst of Letterman’s relationship with now-wife Regina Lasko, sources told The Post.
It was unclear whether Letterman’s fling with Birkitt overlapped with his trysts with other women in the office.
One fling was an alleged affair with another of the show’s staffers in the late 1990s, People magazine reported yesterday.
A staff source told People the secret paramour was one of Letterman’s “peers, a woman close to him, not an intern.”
“It wasn’t a big deal because he wasn’t married. And we heard he had a girlfriend [Lasko] but she never came around, so it just wasn’t a big deal.”
The source, who said Letterman “wasn’t considered a sex symbol or anything” and “came across a lot older than he was,” said this week’s bombshell revelation was a long time coming.
“I’m not surprised it came out,” the source told People. “Even the interns knew what was going on.”
Birkitt was a Wake Forest University grad when she landed a gig as a measly “Late Show” intern in 1996. She soon left for “48 Hours” to become a straight-laced news assistant.
But the news biz proved “a little too serious” for Birkitt, she told the New Hampshire Union Leader in 2004, and she jumped at the chance to go back to Letterman.
Soon, she was opening his mail, helping with his charities, answering his phone and developing an obvious crush on the late night king.
In interviews, Birkitt has virtually gushed about her “fun work environment” and called Letterman “truly the greatest boss I could ever have.”
“Working for Dave is great,” she told her college alumni magazine in 2003.
“Aside from being incredibly funny and personable, he is generous, kind, and is great fun to play catch with,” Birkitt said.
Birkitt became a “Late Show” fan favorite when she appeared in a regular segment in which she’d talk about her social life.
“He started calling once a week, sometimes twice a week,” Birkitt said. “And then I would tell funny stories about my weekend or what he thought were funny stories and I thought were normal.”
She hinted that their on-screen chemistry played out off-screen, as well.
“He teases me in real life, too,” Birkitt recounted in an interview. “But I give it back a lot more in real life.”
A smitten Letterman gave his gal pal on-air pet names, calling her “Monty” and “Smitty, ” and sent his eager sidekick out to do quirky man-on-the street interviews.
She’d good-naturedly don costumes, report the weather from the roof of the Ed Sullivan Theater and banter with Rupert of Hello Deli — another Letterman staple.
She eventually became the funnyman’s personal assistant.
In 2002 and 2006, Letterman dispatched his gal pal to do on-air reports at from the Winter Olympics. She also co-hosted the Tony Mendez show, a featured segment on Letterman.
“No two days are ever alike,” Birkitt once said of her gig. “You come to work each morning really never knowing what will happen next,” she quipped.
The relationship was hot enough that Birkitt’s tuition at Cardozo School of Law was paid for by Letterman, according to Gawker.com.
The affair ended after Lasko gave birth to Letterman’s son, Harry, in 2003, sources said.
But Birkitt remained a Late Show crowd-pleaser.
She hooked up with the alleged extortionist Halderman shortly after his wife of 13 years, Patty, filed for divorce in 2003, a friend of the couple said yesterday.
She had been living with him in his Norwalk, Conn., home for four years, but recently moved out.
Neighbors said a moving van pulled up to the driveway last weekend.
Prior to that, Halderman and Birkitt seemed happy, but “they weren’t all lovey-dovey,” said their next-door neighbor, Kevin Lane, 48, who recently hosted the pair at a backyard barbecue.
“They’d kind of be more private that way,” said Lane.
Halderman’s two youngest kids, Jimmy and Anna Lee — who recently moved to Colorado with their mom — were often at the house with the couple.
Birkitt always spoke highly of Letterman, and joked about how she’d recommend movies to him, Lane noted.
The neighbor said he was stunned to hear about the alleged extortion attempt, noting that “it would never cross my mind” that Halderman would be involved in such a scheme.
“I’m a little puzzled, more than shocked,” Lane said.
Halderman and Birkitt were talking marriage when they suddenly split up, according to a friend of the couple.
“They were making long-term plans,” the pal said yesterday. “I don’t know what happened. She moved out. He was devastated.”
Birkitt apparently left behind evidence, including photos, of her steamy affair with Letterman.
Halderman apparently decided to put them to use to make some quick money, sources said.
“I don’t know what he was thinking but I know he didn’t have any money,” said one long-time friend.
Sources at Birkitt’s Upper West Side apartment said she hasn’t been spotted there since the day before Letterman’s announcement.
She couldn’t be reached yesterday.
“I would think she was as blindsided as the rest of us,” a friend said.
“I cannot imagine that Joe would have told her about it. If he did, Stephanie would have tried to talk sense into him.”
Meanwhile, contacted by The Post yesterday, several current and former female assistants of Letterman’s declined comment.
“I was a good assistant, and a good assistant would never comment on his personal life,” longtime Letterman aide Laurie Diamond told a reporter at her Central Park South apartment.
Media experts yesterday said Letterman deftly handled the alleged extortion plot, and probably won’t suffer negative fallout from viewers.
“He took control of the situation by getting out in front of it,” said Brad Adgate, senior vice president at Horizon Media, a TV advertising consulting firm. “The timing was kind of designed to avoid the worst of the press scrum.”
Outside Letterman’s studio yesterday, crew members were supportive.
“His staff respects that he came out and was straight and honest,” said one. “He’s a family guy who had sex with some of his employees.
“No one thinks less of him.”
Pot, meet kettle!
David Letterman has made late-night hay of high-profile sex scandals, but now that he’s joined their ranks, some of his old wisecracks may be hitting too close to home:
“I really have to hand it to the White House. Around here, we can’t even get the interns to work the copy machine.”
“President Clinton has gotten himself a new dog . . . He’s teaching the dog to sit up, to beg, to roll over — you know, just like he did with the interns.”
“You may think you have a stressful job, but since she’s been a senator, Hillary Clinton, they say, put on 30 pounds. In fact, she has gotten so heavy that today Bill hit on her.”
“The big new scandal breaking here in New York, Eliot Spitzer apparently involved in some kind of prostitution activities — you know what that means: hookers. And right now, Spitzer is huddling with his advisers to develop a drinking problem.”
“Gov. Mark Sanford disappeared . . . and it turned out he was in South America. And then it turned out he was down there because he was sleeping with a woman from Argentina. Once again, foreigners taking jobs that Americans won’t do.”
Additional reporting by Kevin Fasick and Kelly Magee