Podcast’s runaway success has inspired online commenters to carry out their own investigations – a phenomenon which at last seems to have been acknowledged by the show

“I was just curious like everybody else … I just figured out where he lives and found out it wasn’t far,” a Reddit user messaged me late last month.

The “he” the user was describing was Jay, the prosecution’s main witness in the 1999 murder of Hae Min Lee. That’s the Baltimore case which Serial, the viral podcast from the producers of This American Life, has been reinvestigating for the last two months. It has garnered the rapt attention of over 5 million downloaders. And it will all end next week. A second season will deal with a different case.

Jay has not participated in the podcast. This has succeeded only in making him a more interesting target to wannabe detectives. Exhibit A: this user had written on the Reddit that he had driven by Jay’s house and seen him. Perhaps the Redditor was lying, I thought to myself, but I had to ask: Did he have any qualms about doing that, as a relative stranger to the case?

“No, not really,” he replied. “I had no plans of making contact or sitting outside and waiting.” He simply wanted to see the house, and Jay.

Creepy, right? Yet a couple of weeks after trading these messages, I listened to an episode where Sarah Koenig, the show’s host, told a similar story. Needing some answers, she drove straight up to Jay’s house with no warning. This, she admitted, was a “dick move”. Koenig actually knocked on the door. Inside, she and a producer spoke to Jay without recording the conversation. And when they got back to the car they proceeded to narrate the encounter back to us, without quite saying if Jay approved. We only know that he subsequently declined an interview.

In other words, there are moments where the line between the journalist and the Redditor is not as clear as we would like.

Since I last wrote about it for the Guardian, the plot in Serial, as described by Koenig, has certainly thickened. But then, so has everything else: the audience, the criticism and the backlash to the criticism. Most of all, the online discussion by amateur detectives has blossomed further. The subreddit devoted to the podcast now draws more than 700,000 unique views a month.

Facebook Twitter Pinterest An undated photo provided by Yusuf Syed shows his brother, Adnan Syed. Photograph: Courtesy Yusef Syed/AP

The general outlines of the crime, however, haven’t changed much since the first episode. On 13 January 1999, someone strangled Lee. Her body was only found much later, buried in a park. Jay told the police that Adnan Syed, Lee’s ex-boyfriend, was the killer. Two trials, a fairly thin evidentiary record, one plea deal for Jay, and an uneven defense lawyer followed. Ultimately, Syed was convicted. He maintains his innocence. He’s been in prison since his conviction.

Enter Serial, and Koenig. Her exploration of the case has proven addictive. But the serialised approach has invited people, in a way it has never been clear Serial’s producers anticipated, to Monday-morning-quarterback the investigation. The resulting online discussions have been fractious and occasionally taken, in the way of the internet, a turn for the insane. The show has ignored those discussions, even where it seems like they might be relevant. Today’s episode, for example, was titled Rumours. And it addressed some stories that had been floating around Reddit for weeks, without ever mentioning Reddit itself. (I contacted Serial’s producers for comment on Reddit’s relationship to their reporting, but they declined.)

It’s easy to dismiss all this as “just Reddit,” because so much of what’s gone on there has really been about the obsessive armchair-detective types. And yet something else has happened too: the people who are actually involved in the case have used the internet to push back.

The starkest example of that came when Lee’s brother, whom Serial producers had evidently not been able to reach, wrote a post on the subreddit on 18 November. He titled it, “I am Hae’s brother - Do not AMA [Ask Me Anything]”. In it he told the redditors that they were “disgusting,” that “TO ME ITS REAL LIFE.” He seemed less bothered by the podcast than the online discussions themselves. The redditors, generally, seemed chastened. “I am very sorry for your loss,” begins the top comment. (A Reddit moderator, Jacob White, told me then that they are not 100% certain that this poster was actually Hae’s brother. But, he added, “For our subreddit’s uses however, I have confidence enough for the users to carry on conversation. If that makes sense.”)

Another person who surfaced on Reddit about two weeks ago is Tanveer Syed, 38. He’s Adnan’s older brother, and I spoke with him by phone. His first subreddit intervention came because several of the redditors had seized on a “fact” about Tanveer himself. Someone in the defense lawyer’s office had written a note in the file saying Tanveer had called Adnan a “masterful liar.” Tanveer denies this. He says the law clerk misconstrued his stories about Adnan, that he’d only said Adnan told ordinary teenager’s lies about where he was going out to at night.

Specifically, Tanveer says, he’d never have used the phrase “masterful liar,” because to him it’s “awkward language.” But that phrase kept surfacing on the Reddit, he and his wife noticed. And after several weeks of this, they’d had enough. One night, he was “putting my 10-month-old to sleep, and my wife came in and was like: ‘They’re talking about the masterful liar thing again!’” And so he went online to correct them.

Since then Tanveer has intervened several times on the subreddit. I asked him about the emotional toll I assumed this must take on him, but Tanveer was sanguine. It didn’t bother him as much as it bothered his younger brother Yusuf, he said. (Yusuf recently told the Guardian’s Jon Ronson that he’d found Reddit “toxic,” though he also had trouble looking away from it.)

“I had 21 years of my life before it got ruined by Adnan getting arrested,” Tanveer said. But his youngest brother had been in second grade. Tanveer attended the trial; he was used to people attacking his brother’s credibility. Yusuf, meanwhile, who’d been so young, was “seeing all this stuff, like most people, for the first time”.

Recently Tanveer actually found himself on the phone with Adnan, trying to explain the online furor over Serial. Adnan has no experience of social media, he says, so Tanveer had to find another metaphor to explain things. “Reddit is like road rage,” he says he told Adnan. People were very reactive and emotional. And under cover of anonymity, lots felt free to say things they would never say to Adnan’s face. “For Adnan, it was hard to fathom because Adnan’s been in jail,” Tanveer said. “Adnan said: ‘In my world, if you’re not ready to say something to someone’s face, you don’t say it.’”

Tanveer and Adnan are not alone in seizing on the frustrating anonymity of these people on the internet. In the last week, I also spoke to Rabia Chaudry, the family friend who alerted Koenig to the case, about her involvement with Reddit. Early on, she was an active user. But a few weeks ago, she publicly declared she’d deleted her Reddit account.

At the time, as a regular lurker on the subreddit, I could completely see why. After the first few weeks, other users had begun to describe Rabia in terms more appropriate to a cartoon villainess. People resented her unqualified advocacy of Adnan’s innocence, and their resentment inflated her into a character for them to bat around in their discussions. Family and friends still send her screenshots, sometimes. “And it’s hard, sometimes there are these really, deeply personal attacks,” she said. “Me and Adnan’s family, you know, his loved ones, might take things personally… But why are strangers taking things so personally? I don’t get it. It’s so toxic.”

Both Tanveer and Rabia did have some theories as to why some users were so invested. They suggested that some anonymous users may be close to the case, though they’re not admitting it. They couldn’t prove anyone’s identity, though. In fact, it’s hard to definitively prove that anyone is on Reddit unless they voluntarily submit to verification. We only know, for example, that the person claiming to be Hae’s brother who posted on Reddit was that person through the confirmation the moderators sought. The rumour that Jay himself was on the reddit, reported last week by Ronson – well, the moderators deny it. And even Tanveer told me he thought that was a misunderstanding.

As for myself, after weeks of these meta-conversations, I don’t know that any of the online obsessiveness about Serial has a clear explanation. The phrase I keep coming back to, instead, is the one with which this article opens: “I was just curious like everybody else.” I’d never have driven up to Jay’s house unannounced, not even as a reporter with several months of work under my belt like Koenig. But I can understand the pull. Investigative reporting, like storytelling, or like listening to stories, can become its own kind of hypnosis.

Because I can’t discuss these issues with Koenig herself, I emailed Pamela Colloff for some insight. Colloff is an award-winning reporter for the Texas Monthly, where she has written long investigative crime pieces for years. I asked her whether she’d ever consider opening up her reporting to a serialised format the way Koenig has. She replied that though she’d been enjoying listening to Serial, she wouldn’t present a story this way herself.

“Doing so would create an ethical minefield, at least for me,” Colloff wrote. “Good crime writing requires suspense, but stretching that out over a protracted period of time can be problematic. Is it OK for us to wonder for two or three months what the deal is with Jay, to borrow a phrase from the podcast? Or should we be presented with all relevant information about Jay at one time?”

In part that’s because there is an additional ethical burden associated with crime reporting: “The evidence you uncover, and the way you frame the story, can have tremendous influence on the case itself.”

The participants in this case do feel that influence, by the way. When I spoke to Rabia this past weekend, she was very concerned that the latest Serial episode, about Adnan’s defense lawyer, might affect his future appeals. They’re based in a theory known as “ineffective assistance of counsel.” Koenig had presented Adnan as having had more or less total faith in his defence attorney at the time of the trial. But Rabia had spoken to Adnan since and she said he was upset. Adnan, Rabia says, had told Koenig that his confidence in the attorney had since been undermined by what he’d learned after the trail. But Koenig hadn’t aired that part of the interview.

“He was hurt by it,” Rabia said. “The fact that he told Sarah the whole thing, and it wasn’t reported like that, bothered him. And it bothered me.” She says she spoke to Koenig about it. Rabia also says she does not think Koenig intended to harm Adnan’s defense in any way.

At the end of today’s episode, Koenig seemed to me to be addressing this. She talked about a letter from Adnan, dated “a few weeks ago,” in which he tried to explain some things about his relationship to her. “Adnan is obviously aware of this podcast, that it’s out in the world and I could tell that my story had messed with his equilibrium,” she said. She added that she knew she had “yank[ed] this door open again to the outside world and to all its doubts about Adnan’s integrity.”

And as she said this all I could think was about how yes, this is exactly the problem with doing journalism at all. The “ethics” are situational, and not always as clear as anyone would like. You might think you are doing a simple crime podcast, simply presenting the facts. And then you become a sensation, as Serial has, and the story falls to the mercy of the thousands, even millions, of bored and curious people on the internet.