What can The Case Against Adnan Syed tell us that we don't already know?

Now Oscar-nominated documentarian Amy Berg returns to the case for a four-part series from Sky and HBO.

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The Case Against Adnan Syed re-examines the circumstances surrounding the murder of 17-year-old Lee, whose body was found partially buried in a park in Baltimore, Maryland in 1999. Her ex-boyfriend, Adnan Syed, was convicted for the crime in February 2000. Syed has claimed his innocence ever since.

In the five years since Serial was released, its episodes have been downloaded over 175 million times. Fans have dissected every element of the story, while the courts have examined – and denied – Syed's request for a retrial.

The question is therefore: what can a new series reveal about the case that Serial listeners don't already know?

Berg didn't hesitate when she was asked to lead a new documentary about the case in 2015, feeling there was plenty that had been left unsaid after the podcast.

“[The story] had so many elements of things I wanted to explore," she says. "The cross-cultural issues faced in Baltimore; high school students and how they were dealing with something 20 years later that was so dramatic.

"And it had the benchmarks for a wrongful conviction case based on the way the detective work was done,” she adds. “Just everything resting on one person’s testimony, rather than corroborating evidence and DNA, and fingerprints and all of that stuff. So I was really just interested in the state’s case and what was going to happen next.”

She also explains that her aim was to give greater presence to the victim, 17-year-old Hae Min Lee. In the series she features via voice-over readings from her diary and animated sequences.

“I didn’t feel like I had a great understanding of Hae Min Lee from the podcast or much that I read afterwards, just because Sarah was trying to solve the case or figure out what happened with the case. Oftentimes I think in these types of stories the victims get lost in that narrative,” she says. “Episode one [of The Case Against Adnan Syed] was always going to be about Hae. That was really important.”

She also did her best to dig up new information that was not presented in Serial, hiring a team of investigators to look through all of the case files.

“I wanted to have a team of people who knew how to get documents and really dig in,” she says. “And these guys know a lot of people in Maryland, and they were very helpful for us with that, and investigating random rabbit holes that would have taken up years and years of our time.”

Though some of the early criticism surrounding the documentary has suggested bias in favour of Syed, Berg argues that she was approaching it from an entirely objective standpoint. "I was very clear with our investigators that we were looking for anything, even if it included evidence against Adnan," she says.

Berg claims that what she discovered during production made her question some of the police's actions in the original investigation: "You look at these old cases and you’re just kind of wondering why they didn’t talk to the main people in a person’s life, or just keep good records or request her pager records. Hae was a pager. She paged everybody. And there are no pager records in this story, anywhere."

While an examination of pager records does not feature in either the original trial or the podcast, they have been part of the wider discussion in the years since. Berg argues that this is just one example of how 'true crime' documentaries can help draw public attention to important issues by way of entertainment.

"Until there are prosecutors who are willing to take cases and evidence to be tested, take cases to trial so that justice can be served, I think the documentary form is actually useful," she says, "because there are so many things that need to be exposed to the public that are being hidden in files."

The Case Against Adnan Syed will air from 1st April on Sky Atlantic and NOW TV