{alltv} Questions, surprises just won't die in 'The Killing'

Producers of AMC's twisty murder mystery The Killing sure knew how to guarantee a second season — and if you haven't watched Sunday's finale yet, read no further.

or those still with us, the finale never answered the central question for viewers: Who killed teenager Rosie Larsen? Instead, it planted four major cliffhangers: Larsen's grief-stricken mother, Mitch (Michelle Forbes), ditched her family; Stephen Holder (Joel Kinnaman), the hangdog partner of lead detective Sarah Linden (Mireille Enos) was revealed to be a bad guy, faking evidence that tied Darren Richmond to the murder; Linden learned of Holder's deceit only after she'd finally boarded a plane to California with her son, ending her job; and in a freeze-frame finish, Belko (Brendan Sexton III), a Larsen employee and family friend, was about to assassinate mayoral candidate Richmond (Billy Campbell), the most recent — but, like so many others in this 13-episode season, apparently innocent — suspect.

Left unclear: Who was Holder working for? And who did kill Rosie, after a trove of red herrings didn't pan out?

"What it does is clearly leaves us with a lot of fascinating questions," says executive producer Veena Sud (Cold Case). "No one is who they seem, and who would know?"

Some fans will surely be frustrated by the cult hit's lack of closure, but Sud says she always had it in mind. She'd been coy all along about whether the murder would be solved in this first season. "My philosophy was … let's not have a formula" that adheres to TV convention. "If we marry ourselves to the idea of having to stop at the end of the season, we're going to fall into the same trap."

Ditto for the June 5 episode, which brought the plot to a standstill by focusing entirely on the relationship between Linden and Holder, making the former narcotics detective and meth addict — and her ostensible replacement — a more sympathetic character.

Forbrydelsen, the Danish series on which The Killing is based, revealed the murderer at the end of its 20-episode first season: Vagn, a family friend who was the parallel of Belko. But the American ending was deliberately changed so viewers couldn't predict the outcome.

Sud says she can't worry about fans' impatience. "The only paradigm I have right now is how we felt as writers, and there was a lot of excitement (with) tons of on-the-edge-of-your-seat moments." They finished writing the season after the show premiered, so she had some idea of prospects for its return, though AMC officially renewed it just last week. And she promises loose ends eventually will be tied: "The Rosie Larsen case in Season 2 will in fact be solved, and there will be a new case."

She won't say how quickly, or which cast members will return. But AMC officials say they won't make viewers wait until next spring to find out what happens. They're planning to bring the show back early next year.