Documentary film-maker Erin Lee Carr specializes in locating the real story behind what would otherwise be clickbait: her feature debut Thought Crimes analyzed the so-called “cannibal cop” and found a guy at the mercy of his own narrative, while her follow-up Mommy Dead and Dearest captured the passion and obsession of the Dee Dee Blanchard case now popularized by the drama series The Act. So when most people looked at the account of Michelle Carter, a Massachusetts teen accused of hounding her boyfriend to a tragic suicide, they saw nothing more than scandal. Carr looked a little closer, however, and discovered a layered saga with the potential to speak volumes about the public beyond the courtroom.

“One of the things I enjoyed about this project – and I use the word ‘enjoyed’ carefully, because this is a film about suicide – it’s that there was a lot of societal reckoning,” Carr tells the Guardian over the phone, a few days before her latest effort I Love You, Now Die premieres on HBO. “This case covers so much: free speech, mental health, girlhood, boyhood. For me, it was in part about feminism, which speaks to how we view criminal cases involving women through a set of archetypes. There were so many angles through which we could explore this case.”

Carter had landed in the middle of a media frenzy when the shocking details of her relationship with the deceased came to light. Carter had spent a little over two years exchanging text messages and other online communiques with one Conrad Roy, a young man she had met while on vacation in Florida. Though they only lived a brief drive from one another back in New England, their interactions were limited almost solely to the realm of the digital, where the intense bond between them slowly soured. Carter began sending increasingly disturbing sentiments to Roy, eventually building up to exhortations for him to take his own life. When a distraught Roy sealed himself in his exhaust-filled car and stumbled out after having second thoughts, it was Carter that encouraged – commanded, some alleged – him to get back inside.

The case was literally unprecedented, a new standard-setter for manslaughter allegations with its assertion that a killing could be carried out secondhand via text message. Carr’s film crystallizes just how complex pulling off that legal gambit had to be to succeed, as counsel on both sides repeatedly defined and redefined the terms of Roy and Carter’s mental health. Their saga started to resemble an after-school special supercharged by technological connectivity. Carter herself invoked Romeo and Juliet in their texting; the comparison, in all its overcooked dramatics and rash action, was apt.

The citizens of the Commonwealth of Massachusetts saw red during the ensuing trial, placing the blame for Roy’s death squarely on Carter as an ice-cold manipulator. Carr wanted to take a more studied, nuanced approach to a subject she saw as wrestling with her own demons of loneliness and delusion. “At first I thought it was all inhuman,” the director admits. “I mean, who talks to another person like that? So there was an evolution for me, in my thinking. Being part of this story in a long-term way helped me come to understand what Michelle was dealing with.”

Carr wanted to give everyone involved with the litigation a fair shake, to show how Carter’s supposed predation could have been a function of her own instability. She had gone to the Bay State with the intention of producing an episode for a series she was planning at the time, but as she delved into the court documents and archival materials, she got a sense that she had struck on something bigger. She dedicated herself to learning everything she could about the sad tale of Carter and Roy, doing the journalistic legwork of conducting interviews and putting together quotes. But embedding herself in the scene, and gaining entry to the courtroom proceedings as the lone video presence, proved no simple feat.

“Access on this one was deeply difficult,” Carr remembers. “Nobody wanted to talk to some goon from Brooklyn. It was about us continually asking but not bothering people. In terms of the court system, I feel there was a lot of luck involved. They basically told us, ‘You know what? Uh, yeah, you guys can have your shot.’ We showed up the first day in court for opening statements, and if you’re the camera inside the courtroom, that means you have to be the pool camera providing footage for the news organizations. We had to make sure our footage was relayed back to all the news teams, and on day one, everything was malfunctioning.”

Michelle Carter in I Love You, Now Die. Photograph: HBO

Carr laughs as she continues reminiscing about her time in these particular trenches: “The first day, the video feed wasn’t going through, and suddenly we’re the only ones standing between the news and their coverage of this crazy national case. People were losing their minds at us. They had jobs to do! They were like, ‘What the fuck is happening, who are these HBO people?’ I started to have a little meltdown. I turned to one guy, and asked what he thought the problem is, if he just had to take a guess. He says it could be any number of things, and I’m asking him to just take a wild guess as to what it could possibly be. He’s like, ‘I don’t know, an extension cord out of the converter?’ We changed out the cord during the next recess, and of course that was it. I’m not a religious person, but I prayed to whoever exists in the eternal in that moment and thanked them.”

Snafus notwithstanding, Carr got closer to the heart of the dark, confounding situation than anyone else. All the while, as she gained the locals’ trust and developed a personal connection to her material, she strove to remain mindful of her professional obligations. “You have to be objective as a journalist,” she says. “But here I am as a documentary film-maker, adding music to some scenes and editing others. You see the text messages when I want you to see the text messages … You need to remain unbiased when you’re reporting on a murder trial, and I don’t feel that’s something I’m naturally gifted at, nor do I do it on a daily basis. There’s conflict in that, everyone struggles with it. What I try to keep in mind is: what are the facts? What’s the evidence? Who are the key people involved, and how can I talk to them? That’s what I include in the piece. There’s no first-person, no voiceover.”

Her work searches for the truth along with a hard-fought decency, a belief that figures the mass media may vilify still contain a core of humanity. She sees this notion of empathy as a foundation of the true crime genre currently dominant in American culture, maybe even the secret ingredient that’s made it so recently ubiquitous. If the people would only look past the kneejerk rage that the Carter case inspires on first glance, they’d be wounded by the same pain that drew Carr to this sordid tale – a pain emanating from both sides, outward in every direction.

“True crime has a way of creating a visceral, physical reaction,” Carr firmly states. “There’s nothing like hearing about other people’s hurt. We’re herd animals, and we don’t want to see other people hurting. It’s like sports, with built-in stakes that you get invested in. This is a story about human beings, people also struggling with mental health issues will see it, and so we have to make sure to be compassionate while reporting on scandal.”