Warning: Stop reading if you have yet to watch tonight's killer Dexter season finale. Everyone else, see below for my exclusive postmortem with executive producer Clyde Phillips. Among the hot topics discussed: When (and why) was the decision made to whack Rita? Will she return as a ghost? What was the alternate cliff-hanging twist? And when the hell will Deb figure out the truth about Dex?

When was the decision made to kill off Rita?
CLYDE PHILLIPS: I would say we made the decision pretty late in the season. We didn't quite know what we were going to do [in the finale].

Why Rita?
PHILLIPS: The story evolved and it kind of became inevitable. We knew that we had to do more than kill Trinity. It's a little bit of a corner that we paint ourselves into. Last year we tried to avoid that and actually I think we didn't do as well as we could have. We killed off Jimmy Smits' character [in the 11th episode] of 12 episodes and then we had to figure out what we were going to do in the 12th episode. This season, we knew that we were going to take Trinity out in the 12th episode and we think that the audience knew that, too. We had to raise the bar to as high as possible and then figure out what to do next year.

How did Julie Benz take the news that she was leaving the show?
PHILLIPS: She wasn't happy. She loved being with us. We loved having her with us. She took it… professionally. She was greatly disappointed. She's a professional. She works in television. She knew that this was a possibility.

Did Trinity tell Rita about Dexter before he killed her?
PHILLIPS: I don't know the answer to that question. We haven't talked about next season. But [my gut says] I would think that he did not tell her.

Might she return as a ghost like Dex's dad?
PHILLIPS: The answer, at he moment, is no. However, had you asked me two years ago if Lundy was coming back I would've said no. We didn't know he was coming back until this year. It just seemed expedient to the story - to Dexter's story and to Deb's story.

Some people thought the game-changing twist was going to involve Deb figuring out that Dexter is a serial killer. How much longer can you stretch out that story before you pay it off?
PHILLIPS: We've bounced that around the [writers] room. But once we do that… want to talk about game-changers? Once we do that, the game is changed in a way that we just don't know how to anticipate just yet.

Will next season be about Dexter juggling serial killing and single fatherhood?
PHILLIPS: He is a single father. But, beyond that, we don't know. We don't know if there's going to be what we call "a Big Bad," like Jimmy Smiths and John Lithgow, or if it's going to be more individual, stand-alone stories.

I understand you wrote two endings to throw people off. What was the other ending?
PHILLIPS: While Dexter was packing to leave, he saw on the television that a child murderer had just escaped from prison. Either escaped or fallen thru the cracks. So he's thinking, "Do I join Rita on vacation or do I…" and then he looks towards the camera and he has this big decision.

That would've been disappointing.
PHILLIPS: [Laughs] Yeah. Compared to this? Are you kidding?