The Walking Dead creator Robert Kirkman knows exactly how the zombie outbreak started, but he won't ever explain it, at least not in the comic, he said during a New York Comic Con panel today.

"I'll never reveal what the source of the outbreak is in the comic," he said. "I'm never going to do that. I know what caused it."

The issue, Kirkman said, was that having the cast of the comic find out just doesn't fit in with the story.

"What am I going to do?" he asked. "Have a scientist walk up and say the president was working with NASA …

"Any effort to have them become aware of the source would bring the comic into the realm of science fiction and I don’t think that would be necessary."

If the comic ever ends, though, he said, "I'll publish a little book that explains it because I'll be broke."

Spoiler warning: This story contains discussion of the entire comic run and includes spoilers of major events in the comics. It also includes discussion of the TV show up to, but not including, the upcoming season premiere.

Kirkman took the stage of the Hammerstein Ballroom in New York City this afternoon along with the comic's editor Sean Mackiewicz to discuss The Walking Dead series, now on issue 159.

The talk kicked off with discussion of the comic's Whisperers and the Whisperer War that pits the established survivors of the series against a group of people who wear the skin of the dead and live among massive herds of zombies.

Kirkman said he came up with the idea for the Whisperers, who only speak in whispers to avoid the notice of the zombies, while pondering how other people might have survived the outbreak.

"I always wanted to show how different people have survived," Kirkman said. "These people are so beaten down by the zombie apocalypse they they have tried to abandon all humanity.

"They see themselves as animals and try to embrace that."

Among the questions about the Whisperers was one about Fear the Walking Dead's Nick, who often covers himself in zombie blood so he can move freely among the undead.

"Is Nick going to be a Whisperer?" a fan asked.

"No comment," Kirkman responded.

The Whisper Wars brought with it a surprising change in the relationship between Rick Grimes and bat wielding psychopath Negan.

"I think the idea there is that Rick has had him in this cell for so long that there is an understanding there," Kirkman said. "He gets who he is as a human being. So there is a softening to some extent of their relationship.

"Negan has gone out of his way to prove he's not against him anymore. He had a chance to escape and didn't. And then he did escape and proved it was for a worthy cause: cutting off someone's head. "

Negan, it turns out, was a hot topic of conversation during the panel. Perhaps that's not surprising, given that The Walking Dead television show returns on Oct. 23 with the conclusion of Negan's introduction and the death of … someone.

While the comic has Negan brutally beating Glenn to death, the television show hasn't always followed the same path. So it's unclear who will die on the Oct. 23 premiere.

One fan got up to beg Kirkman not to kill off Glenn because he is the show's only Asian and it would upsetting to see him killed off again.

"There is a very good chance you will be very happy," Kirkman replied. "There is a very good change you will be very upset.

"I won’t be there, so I won’t care."

Kirkman added that he tried to represent as many minorities in his comic and the show as realistically as possible.

"Am I going to keep this guy alive because he's Asian?," he said. "Then I'm being racist in a different kind of way."

"Just know this: Whoever dies, they were dead this time last year or earlier. So anything you're saying right now is completely pointless."

Besides, it turns out that Glenn was supposed to die much earlier in the comic.

"I ended up changing my mind," Kirkman said. "I eve had a cover drawn to show him dying."

Negan was meant to die by now in the comics too, he added.

"Originally, I only had him in four or five issues," he said. "When I wrote issue 100 I was like, 'I love this guy so much.'"

The original plan, he said, was to have Rick deliver Negan's head in a box to Maggie as an apology after she takes over Hilltop.

Finally, someone asked Kirkman what sort of non-The Walking Dead plans he has.

"I have three horror shows on air [The Walking Dead, Fear the Walking Dead and Outcast]," he said. "I'd like to do some non-horror stuff now."