The Investigation of Lucy Letby, Netflix’s new documentary examining one of Britain’s most harrowing criminal cases, ends on an uncomfortable question: is she actually guilty?
Letby, now 36, is serving a whole life order for the murder of seven babies and the attempted murder of seven others. She worked as a neonatal nurse at the Countess of Chester Hospital, where a series of unexplained collapses and deaths took place.
During her trial, prosecutors argued that Letby deliberately injected air into babies’ bloodstreams, poisoned others with insulin, and sabotaged care. She has always denied murdering or attempting to harm any child.
Since her conviction in 2023, a growing number of experts have raised concerns about the evidence used against her. That doubt hangs over the final moments of Netflix’s documentary, which leaves viewers asking a question many thought was already settled.
Netflix documentary revisits evidence that convicted Lucy Letby
The first half of The Investigation of Lucy Letby carefully retraces how police built their case.
It revisits expert testimony from Dr Dewi Evans, whose reviews of medical records helped focus attention on Letby, alongside evidence recovered from her home — including handwritten notes containing phrases such as “I am evil” and “I did this”.
The documentary also highlights Letby’s presence during many of the babies’ collapses, as well as her collection of neonatal handover notes, which were organised and dated.
For many viewers, this material reinforces the prosecution’s case. As one Reddit user put it: “Really damning stuff.”
But the documentary does not stop there.
Midway through, it shifts focus to Mark McDonald, a criminal barrister who argues that Letby’s conviction represents a possible miscarriage of justice.
McDonald points out that there is no CCTV footage of Letby harming any child, and that no staff member ever witnessed her committing an attack. He also challenges the interpretation of Letby’s handwritten notes, arguing she was encouraged during counselling to write down intrusive thoughts after being removed from the neonatal unit.
According to Letby, she felt overwhelming guilt — not because she had committed crimes, but because she was on duty when babies died.
McDonald also accuses Dr Evans of providing biased testimony to police, an allegation Evans has denied.
The documentary then introduces Dr Shoo Lee, whose research on air embolism was cited during Letby’s trial. Lee says he became concerned his work may have been misinterpreted.
“If my paper had been misused,” he says, “then we had a big problem.”
Lee later led an independent expert panel that reviewed each death. Their conclusion: there was no evidence of deliberate harm.
Viewers split as calls for Lucy Letby retrial grow
Reaction to the documentary has been sharply divided.
Some viewers say the film convinced them that Letby should be granted a retrial.
“I am convinced she isn’t guilty,” one viewer wrote on X. “There was no concrete evidence, just circumstances that got her convicted.”
Another argued: “At the very least, she didn’t get a fair trial.”
Others focused on the lack of eyewitness testimony. “Watching the Lucy Letby doc and [there is] no way not one staff member didn’t catch her red-handed in harming these babies. That seems sus to me,” one wrote.
Several viewers pointed to comments from Dr John Gibbs, a retired consultant paediatrician who worked at the same hospital. In the final moments of the documentary, he admits living with what he calls a “tiny guilt” over the possibility that the wrong person was convicted.
Former MP Nadine Dorries has also publicly backed calls for a retrial, calling it the “biggest justice scandal this country has ever witnessed”.
Others online aren’t as convinced by the documentary.
“I heard this documentary would blow the case open and be damming in respect of a mistrial. The complete opposite happened as far as I can tell. She’s guilty as hell,” one user wrote on Reddit.
The documentary features unseen footage from her arrests. “Just on her behaviour alone during her arrests makes me believe she’s guilty,” another user observed.
As one interviewee puts it in the doc: “If this woman is innocent, then she is pretty unlucky.”
Could Lucy Letby get a retrial?
Whether Lucy Letby will receive a retrial remains uncertain.
She has already lost two appeals. However, her case is currently being reviewed by the Criminal Cases Review Commission, which examines potential miscarriages of justice.
The commission will also consider evidence presented to the Thirlwall Inquiry, the public inquiry examining events at the Countess of Chester Hospital. Its final report is expected around Easter.
If the CCRC refers the case to the Court of Appeal, judges will decide whether Letby’s conviction is unsafe — a decision that could lead to a retrial.
In January, the Crown Prosecution Service confirmed it would not pursue additional charges against Letby following further allegations submitted by police, stating that the evidential threshold had not been met.
Cheshire Police said the decision was “not the outcome that we had anticipated”.
Read more: Netflix viewers call out Lucy Letby doc for using ‘fake AI faces’ in ‘weird’ interviews
The Investigation of Lucy Letby is streaming on Netflix now.
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