Letterman and Stephanie Birkitt

A "Late Show" office worker in 1997, Birkitt quickly developed a role as Letterman's Girl Friday. She went on to appear in several skits as his comic foil. Behind the scenes, their relationship became intimate, sources said.

"The creepy relationship that Letterman maintained with Stephanie was obvious and not normal," an insider said. "She was able to do anything and everything ... It was pretty well known that Stephanie was the one that Letterman was having fun with."

Until this week, she was best known as David Letterman’s former assistant — a pretty and peppy young woman whose appearances on his show made her a minor celebrity.

Now, Stephanie Birkitt’s name has been dragged through the mud as she emerged as one of the women at the center of the extortion plot against the CBS funnyman.

Birkitt, 34, dated accused extortionist Robert (Joe) Halderman before the Emmy Award-winning producer was charged with concocting a bizarre plot to expose Letterman’s dalliances with “Late Show” staffers.

Birkitt is believed to be one of the women Letterman confessed to bedding Thursday.

Letterman’s former “Girl Friday” remained in hiding on Friday.

She has not shied away from expressing her admiration for her boss in the past.

“Aside from being incredibly funny and personable he is generous, kind, and is great fun to play catch with,” Birkitt said in a 2003 interview with a publication of her alma mater, Wake Forest. “I really couldn’t ask for a more fun work environment. Dave is truly the greatest boss I could ever have.”

Birkitt, a New Hampshire native, interned at the show in 1996 while she was still a student.

After graduating a year later, she did production work for CBS’ “48 Hours.” But the gig didn’t suit her.

“I didn’t think I was much of a news hound as it was a little too serious for my personality,” Birkitt told the New Hampshire Union Leader in 2004.

So when she learned that an office job opened up at the “Late Show,” Birkitt pounced.

She got the job, and not long after, found herself taking a call from Letterman.

“He asked if I wouldn’t mind taping [the MTV show] ‘Jackass’ for him,” Birkitt said in a 2004 interview with the Fort Worth Star Telegram.

“He did that a few more times...and then we just kind of developed a phone rapport.”

The unlikely pair’s relationship developed quickly. Letterman began calling Birkitt twice a week — and their conversations eventually became more personal, she said.

“We’d talk about my weekend,” Birkitt told the Star-Telegram. “And he started asking if I had pictures from my weekend, so I showed pictures.”

Birkitt was soon making periodic appearances on the show, often donning costumes and conducting light-hearted interviews.

Letterman often referred to her by a variety of nicknames, including “Monty,” “Smitty” and “Gunter.”

In one of Birkitt’s better-known appearances, she asked “Survivor” castoffs: “Did you see or touch any monkeys?”

An aspiring lawyer since she was a child, Birkitt went to the Benjamin N. Cardozo School of Law in 2005 and passed the Connecticut bar exam in February.