To mark the occasion, we caught up with the show's star - Emmy-nominated actress Mireille Enos. Read on to learn Mireille's thoughts on the controversial season finale, the Sarah / Holder partnership and the "pay-off" that's coming in season two!
When the first season of The Killing was airing, did you get a good sense of the viewer reaction?
"Yeah, because the numbers were really good right from the start, and then they sustained, which was very exciting. Then critics started writing their take on it and basically everything was positive, which was so exciting."
Did fans approach you on the street to talk about the show?
"It's really interesting, the kind of response I would get on the street. People didn't walk up as fans, they walked up like they knew Sarah!
"I had one woman in the grocery store - she was kind of a purple-haired grandma - and I was standing at the deli counter. She realised who I was and just gave me a hug! It was right after the episode where my son goes missing and she just gave me a big old hug!"
You mentioned the 'Missing' episode - did you enjoy exploring Sarah's personal life?
"I did. It was one of the most exciting weeks of shooting in my career. Joel Kinnaman [who plays Stephen Holder] is just an incredible partner to work with, and it was just the two of us. 12 to 14 hours a day, just getting to work with him - it was very exciting."
Are you hoping for more episodes focusing on Sarah's personal life in season two?
"I actually hope that it's woven together - that there's some time given to Sarah's personal life, but that we also drive right through to the end of the case.
"I think the timing was really great [in season one] to give us some of Sarah and also Holder's personal lives, because the audience had been very patient with just these little hints. I think they needed a good hook into these people. But now actually I think the most important thing is the drive to the end of the case."
What is your take on the relationship between Sarah and Holder - especially given that twist in the finale?
"I think that they are two people who are both socially awkward in very different ways. They both have strength and weaknesses, which compliment each other actually. I think because of that 'Missing' episode, there's a real sense of trust [between them].
"I don't know what the twist actually is. My optimistic hope is that he is just a dummy and not a traitor, but I actually don't know how that will turn out."
Sarah is quite a complex character. Are you pleased that The Killing avoided the usual cop show clichés?
"Yes, I'm very pleased. It's so rare that you get to create someone who's three-dimensional. The writing of the show was, I thought, very filmic, but then there's the additional benefit that I got to spend 13 hours telling Sarah's story instead of the 2 hours that a normal film would spend. She's really an incredible person to spend all that time with."
What was your reaction to the controversy surrounding the first season finale?
"I thought the controversy was great. I personally love a cliffhanger - I think it just extends the pleasure of viewing. I know a lot of people were upset about [the ending] but I just tend to think that people talking about the show is good, even if it's controversial talk.
"I think with the people who were the most upset, it's just evidence of how invested they were in the show. And once season two comes back and it finally does get solved, I think they will find that the pay-off was worth it."
How did you feel about being nominated for an Emmy this year?
"Excited and honoured. It's rare to get nominated in the first season of a show. [Getting nominated is] not why you do the work, but because we all worked really hard, it was exciting to be acknowledged in that way."
You previously mentioned that you hadn't watched the Danish version of The Killing to avoid any comparisons. Have you been tempted to dip into the show now that you've wrapped your own season one?
"No, because we're now going into season two, so I think the same would [still] be true for me. I think it would be distracting."
Are you pleased that the US Killing has now established its own identity?
"I am very pleased. I know it was important to [showrunner] Veena [Sud] to maintain the backbone of the [original] show [and] what made the Danish series so popular, but then also to branch out in our own way.
"We seem to have done that successfully. People who loved the Danish version are able to watch the American series and have a different experience, so that's good."
How did you feel when The Killing was picked up for season two?
"Thrilled. It seemed wrong not to get to finish the case."
When did you discover that the killer wouldn't be revealed by the end of season one?
"Just when I got the scripts for the final episode! I had started to have a hunch it might happen around episode 11. We spent that entire episode [focusing] on my son and there were just two episodes to go.
"Because of how slowly it had all been unfolding, I felt skeptical that we would be able to wrap it up in two more episodes. So I wasn't that surprised, but none of us knew until we got the final script."
Do you know anything about what's happening in season two?
"I don't. We start filming in November. The writers are in the room right now, working away!"
Do you feel like the show has opened up new avenues in your career?
"Oh definitely, yeah. Absolutely. I think of the show as being an ensemble, but because I'm thought of as the lead, that has led people to think of me as someone who can carry a story.
"I'm getting more film opportunities - I'm working on World War Z now and then I'm going to be doing Gangster Squad in October. And then there was the Emmy nomination. The whole thing has definitely put me in a different category."
The Killing is released on Blu-ray and DVD on 26 September from Twentieth Century Fox Home Entertainment.