Why are online sleuths so obsessed with true crime cases like Lucy Letby’s? (2025)

Lucy Letby is a convicted serial killer serving a life sentence. The Thirlwell Inquiry (due to conclude early 2025) is currently investigating how an NHS nurse was able to murder at least seven babies and attempt to murder seven more.

But if you spend any time online, Letby’s guilt/innocence is very much an active topic of debate. The idea that this could all be a terrible miscarriage of justice is not just fringe belief held by kooks and conspiracy theorists. David Davis – a knighted former cabinet member – went on GB News to claim he was “90-odd per cent certain” Letby was innocent.

Davis is not alone in doubting the conviction. The New Yorker and The Guardian have both published deep dives that question the evidence and float the possibility of Letby’s innocence. To be clear, freedom of the press and the right to ask questions about our justice system are important to a functioning democracy.

In many ways, the high levels of public interest are entirely understandable. Humans are obsessed with solving mysteries. We’re hardwired to solve puzzles and find patterns, desperate to find order in a chaotic world.

In fiction, a good mystery is always a chart-topper, from Arthur Conan-Doyle’s Sherlock Holmes to Richard Osman’s Thursday Murder Club. So when something truly terrible happens in real life – like the death of a child or an unexplained disappearance – we want to make sense of how something so awful could happen.

But this innocent desire to understand and process has taken an altogether darker tone when it comes to criminal proceedings - and the ease with which wild theories can be spread on the internet. True crime has always attracted outsize interest in the news. But now everyone is a) online and b) hanging out on the same handful of online platforms, any story about a potential crime with mysterious or complex elements can snowball, blurring the line between fact and fiction.

The discussion around the Thirwell Inquiry will keep fuelling a subculture of armchair sleuths whose interest can tip over into something altogether unhealthy and disruptive. There are over 12,000 members of a Reddit community dedicated to discussing Letby’s case. Members attended the trial last year and discussed the proceedings in detail - with at least one person posting in contempt of court. Reddit deleted the offending posts.

The Letby case is only the latest high profile crime that has gripped armchair investigators. When 19-year-old Jay Slater went missing in Tenerife this summer, online speculation exploded. People sent his mother doctored images pretending to have her son held captive. People made up wild stories about criminal underground connections. When his body was found (he’d simply fallen from a height in difficult terrain) and repatriated, people spammed his funeral.

Anything initially mysterious risks spiraling into conjecture. In 2023, when Nicola Bulley vanished while walking her dog, the internet exploded with wild theories. Despite the fact there was no evidence of foul play – and that even a shallow-seeming river can prove treacherous – the case descended into chaos. Private search teams muddied the water, while members of the public impersonated journalists to invade police cordons.

Bulley’s body was recovered from the river and her death was ruled an accidental drowning. But the damage was already done. Her grieving husband received a barrage of online messages from strangers accusing him of hurting his wife. “On top of the trauma of the nightmare that we're in, to then think that all these horrendous things are being said about me towards Nikki,” he told the BBC. “Everyone has a limit."

The social media feeding frenzy recalled the 2022 University of Idaho Massacre. Four college students were stabbed to death in their off-campus home. Layperson investigators went into overdrive; one self-identified “psychic” took to TikTok to randomly accuse local professor Rebecca Scofield of orchestrating the killings. Even when a genuine suspect was arrested, the accusations continued. Scofield sued, but has been left to pick up the pieces.

There was a similar level of obsessive speculation over the disappearance of Gabby Petito in 2021. People pored over her digital footprint and erroneous sightings flooded the investigation. Petito’s body was eventually found in a remote area. She’d been murdered by her boyfriend. That didn’t stop QAnon conspiracy theorists glomming onto the case and making up bizarre theories that Petito was a deep state hoax cooked up by the media to distract from criticism of President Joe Biden.

QAnon is at the more extreme end of online theorising. But the impulse to question the narrative exists on a spectrum. It doesn’t seem to matter to armchair investigators if the truth is a tragic accident or a murder with a definitive suspect. Playing along at home is all too alluring when it’s so easy to find a Reddit thread or X hashtag to follow. Too often we forget that real people are suffering when a stranger-than-fiction story plays out in the news.

Amateurs playing at forensic investigation risk re-traumatising the survivors and victims’ families, wasting police time, and potentially interfering with how a case can be successfully tried. The true crime industrial complex also puts those who work to produce it at unnecessary risk.

Michelle McNamara was a brilliant true crime writer who became consumed by the case of the Golden State Killer. Her commitment to uncovering his identity kept the case alive, and she even worked with the cops to track him down. But constantly immersing herself in the darkness of a man who raped and murdered people in their homes took its toll. Desperate to focus as she fell down online rabbit holes, then finding herself unable to sleep, she self-medicated with a toxic mix of prescription pills she kept secret from her husband, comedian Patton Oswald.

On 21st April 2016, Oswald found McNamara dead in their bed, aged 46, from an accidental overdose. The Golden State Killer was caught just days later.

Amateur sleuthing can be addictive, a hard habit to break. I should know. Last year, after finding a bootleg copy of the New Yorker (it being blocked in the UK only added to my curiosity) I fell into my own Letby armchair sleuthing rabbit hole.

I spent hours combing through the scraps of evidence that circulated online, reading Reddit board discussions like they were my morning paper. I told myself it was a professional interest, that I’m a journalist with a masters in psychology, that my take on the case was more legitimate than randoms sharing outlandish theories online. Right?

I became fixated on the table of nurse rotas versus neonatal deaths, haunted by the idea that perhaps a young person keen to work overtime and stuck in a toxic, failing workplace could become the scapegoat for institutional neglect. Ultimately, I realised that Letby’s guilt or innocence wasn’t the point, my obsession was a projection of my own anxieties resulting from experiences in my own past.

And its an anxious time to be reading the news. Trust in institutions such as the Met Police feels like it’s at an all time low. Senseless death on a mind-breaking scale is everywhere. The idea that we could crack a case or solve a crime is soothing. Being well-informed and able to think critically is healthy. But when people start pulling out the red string – or overstepping by contacting real people connected to a tragedy – you have to pull the plug.

Not to be an armchair psychologist, but that inquisitive energy could probably be redirected into more positive things.

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