Netflix's true crime series Making a Murderer has become a national obsession since its debut in December - prompting lots of media coverage, a late-night spoof and even comment from the White House. Yet the documentary, which casts doubt on the 2005 murder conviction of Steven Avery, has also fallen under some scrutiny about its legitimacy - especially in light of new statements from Avery's ex-fiancé and freshly released transcripts from Nancy Grace that she says proves his guilt.

At the Television Critics Association winter previews Sunday, series' directors Laura Ricciardi and Moira Demos faced reporters in a tense and at times defensive session. They stood by the film's accuracy, their choices and refused to take a side on Avery's guilt or innocence. Here, the top six comments from their session.

1. On the purpose of Making a Murderer: After reading about Avery's case in the New York Times, the directors began making the documentary in an attempt to get questions answered. But they ended up only with more questions. It's muddied, they said, and they encourage people to embrace its ambiguity. Ultimately, their bigger objective was to get people interested in and passionate about the American criminal justice system - all parts of it, even jury duty. "Most of the characters," Ricciardi said, "are elected officials. If you have a prosecutor who runs on conviction rate, why are you surprised when they go to all measures to win?"

2. On their decision to omit evidence. "This is documentary," Demos said. "We are not prosecutors. It would have been impossible for us to submit every piece of evidence. Of course we left out evidence. There would have been no other way to do it. We're not putting on a trial but a film." The question, she said, was if they left out significant details that impact the integrity of the work. "The answer is no."

3. On Avery's ex-fiancé Jodi Stachowski saying he's guilty, and the domestic abuse claims. Ricciardi said she can't speak to what Stachowski is saying now. "When we filmed nine years ago, this is an accurate portrayal of what she was saying at the time." Added Demos: "We have no knowledge of domestic abuse. I don't know what you're referring to."

Making a Murderer: Steven Avery's ex-fiancée says he's not innocent

4. On people's impassioned attempts to get Steven freed. "It's clear people were very affected and wanted to do something. It's understandable people wanted to get involved," Ricciardi said. Demos even said that, to so some degree, they expected the response.

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5. On Avery now. The filmmakers have been in contact with Avery since the show launched, and they have recorded phone calls that might be part of a future series. However, Avery does not have access to the series, Demos said. "He asked the warden and social worker whether he could see it," she said. "His request was denied. When we spoke recently, his focus was mainly on his case. He was representing himself. He was working on a motion to appeal and lost." The story is ongoing, they said, and they're ready to follow developments. They're looking at other stories as well.

6. Do they think Avery did it? No comment. What we're seeing now is history repeating itself, with the media demonizing this man to prove his guilt, Demos said. "We looked into Avery, warts and all. Just because someone is coming forward with a narrative... their interpretation of something doesn't make it factual." She added later, "We do not consider this advocacy journalism in the least. We are not taking sides. We don't have a stake in his innocence or guilt."

What do you think: Did the directors present the case fairly?

Watch: Nancy Grace says Steven Avery is guilty.