Jason Alexander reveals why "Seinfeld" killed Susan

Leave it to Howard Stern to dig up dirty relationship secrets kept under lock and key for 20 years. In an interview Wednesday with Jason Alexander, the unforgettable George Costanza of "Seinfeld," Stern finally closed the case on why George's betrothed Susan was killed off on season 7, right before their wedding -- it was a full-on "Seinfeld" cast conspiracy.

Seemingly the perfect bride for the imperfect man, Susan was accidentally poisoned to death licking wedding invitation envelopes -- an untimely tragedy that nihilistic, commitment-phobic George rejoiced in. But the script-writers weren't just giving George an out; it was for the whole cast, who apparently had problems meshing with the actress' comedic style, Alexander revealed.

"The story goes that she was killed off because you couldn't stand working with her," Stern told Alexander.

Alexander laughed. "This poor girl," he said, couching the truth with compassion. "The actress is this wonderful girl, Ms. [Heidi] Swedberg," Alexander said. "... I love her. She's a terrific girl. I love her. I couldn't figure out how to play off of her," Alexander said, to which Stern accused him of being too gentle.

"Her instincts for doing a scene -- where the comedy was -- and mine were always misfiring," Alexander admitted.

Alexander said that when he first commented to Jerry Seinfeld and Julia Louis Dreyfus about the challenges of hitting comic stride in his scenes with Susan, they told him he was imagining things. But when they later had to do their own bits with her Seinfeld admitted "It's f---ing impossible!"

"Julia actually said, 'I know -- don't you just wanna kill her?'" a snide comment that was inspiration for creator Larry David in the show's third to last season.

"Every time I tell this story I cringe because Heidi is the sweetest," Alexander said.

Although Swedberg lived on past her on-screen death in 1995, her acting career did not survive long past her "Seinfeld" days. Instead, she's fostered a music career teaching and playing ukulele and playing in her own band based in Los Angeles.

On Thursday, Alexander issued an apology to Swedberg and clarified the comments he made in the interview, stressing that the issues stemmed from the character and not the actress herself.

"She was generous and gracious and I am so mad at myself for retelling this story in any way that would diminish her," he said, later adding, "To Heidi, I personally apologize. You are a sweetheart. I actually launched into this on Stern to defend you. But this is why I'm not a lawyer. Now everybody, calm down and just enjoy the reruns and think, 'Why did he think this wasn't working? This is great.'"

Listen to Alexander tell the story to Stern in the clip below: