After Lucy Letby was sentenced to 15 whole-life terms for murdering seven babies and attempting to murder seven others, an inquiry was launched to ensure lessons were learnt.

The Thirlwall Inquiry is examining three broad themes – the experiences of all victims’ parents, how the concerns of clinicians were handled, and to ensure lessons are learnt from the case of the most prolific child serial killer in modern British history.

About 133 witnesses, including parents who lost their children, hospital executives, and Letby’s former colleagues at the Countess of Chester Hospital, have provided live evidence to the inquiry since September, with a further 396 giving written statements.

The closing statements this week come days after a police investigation into corporate manslaughter was widened to include gross negligence manslaughter.

The inquiry also heard that two baby deaths remain the subject of ongoing police investigation, which Letby has been interviewed in prison over.

Inquiry chair Lady Justice Thirlwall is expected to publish her official report in the autumn, outlining the detailed findings and recommendations based on the evidence that has been heard.

This week, the Thirlwall Inquiry is hearing closing submissions from the various interested parties. Here’s what has been said during the key testimonies so far.

Why is it called the Thirwall inquiry and why are there calls for it to be suspended?

Opening the inquiry at Liverpool Town Hall on 10 September last year, Lady Justice Thirlwall said the probe bears her surname so that the parents do not repeatedly see the name of the person convicted of harming their babies.

She said the babies who died or were injured would be at the “heart of the inquiry” and condemned comments at the time that questioned the validity of Letby’s convictions – which the nurse tried and failed to challenge at the Court of Appeal – and some of the evidence used at trial.

The inquiry also remains separate to a 14-member expert panel, led by retired neonatologist Dr Shoo Lee and senior Conservative MP David Davis, which in February said it had analysed medical evidence considered during Letby’s trial and claimed there was no medical evidence that the nurse murdered or attempted to murder 14 premature babies.

Letby’s lawyers have since applied for a review of her case as a “potential miscarriage of justice” by the Criminal Cases Review Commission (CCRC) after two failed bids at the Court of Appeal.

On Monday, the judge said she had received a request last month from lawyers representing former executives at the Countess of Chester Hospital asking for the public inquiry to be suspended.

Lady Justice Thirlwall also said she had recently received a written request from solicitors representing Letby for her to pause the inquiry.

In the letter to the judge, which Sky News has seen, Letby’s lawyers warned Lady Justice Thirlwall that her final report would “not only be redundant but likely unreliable” if it was not put on hold until after the conclusion of the former nurse’s CCRC application.

Letby couldn’t ‘wait to get first death out of the way’

One of the nurses who started as a newly qualified nurse at the Countess of Chester Hospital on the same day as Letby told the inquiry that the serial killer had told her she “can’t wait for her first death to get it out the way”.

The nurse said she thought the comment was “strange” at the time, but she put it down to Letby just making conversation.

She also recalled Letby being “animated” when telling her she had been involved with resuscitation attempts of a child on the ward in 2012.

“It was kind of like she was excited to tell me about it,” the nurse said.

‘Likely’ Letby murdered or attacked more children

Neonatal clinical lead at the Countess of Chester Hospital, Dr Stephen Brearey, told the inquiry that he thought it was “likely” Letby murdered or started to harm babies prior to June 2015.

He agreed that “on reflection” several unexpected collapses and deaths before that date now “appear suspicious”.

Dr Brearey added he did not have concerns about those incidents at the time, saying that hospital staff “thought we were going through a busy or particularly difficult patch”.

The inquiry was told that the dislodgement of breathing tubes, which was how Letby tried to kill Child K, generally occurs on less than 1% of shifts.

However, it happened on 40% of shifts that Letby worked when she was a trainee at Liverpool Women’s Hospital.

Newborn given potentially fatal morphine overdose

Two years before Letby carried out the murder of Child A, she and another nurse gave a potentially fatal dose of morphine to a newborn baby.

Neonatal unit ward deputy ward manager, Yvonne Griffiths, told the inquiry that the infant received 10 times the correct amount of the painkiller at the end of a night shift in July 2013.

Describing it as a “very serious error”, she said the infant could have died if colleagues had not spotted the error an hour later.

Letby was told she had to stop administering controlled drugs as a result of the error, a decision that she told management she was not happy about.

Letby offered ‘tips’ on how to get away with murder

In a WhatsApp exchange in 2017, Letby and union rep Hayley Griffiths discussed the US legal drama How To Get Away With Murder.

The discussion took place a year after the neonatal nurse was moved to clerical duties following concerns she may have been deliberately harming babies.

In a message to Letby, Ms Griffiths wrote: “I’m currently watching a programme called How To Get Away With Murder. I’m learning some good tips.”

To which Letby replied: “I could have given you some tips x.”

Ms Griffiths responded saying she needed “someone to practice on to see if [she] could get away with it”, and Letby replied: “I can think of two people you could practice on and will help you cover it up x.”

The union rep said: “I truly and deeply regret having started that conversation… this is completely unprofessional.”

No support or counselling given to parents

The parents of two triplet boys murdered by Letby told the inquiry they were given no support or counselling after the deaths of their children.

The children died on successive days in June 2016. Letby was their designated nurse and their deaths led to her being removed from the Countess of Chester Hospital’s neonatal unit to a non-patient facing role.

The triplets’ father said: “Following the deaths of our children, we didn’t receive any support or counselling from anyone. Had we received some support, we might have been in a better position to try and act on what our instincts were telling us, which was that something had gone badly wrong.”

Senior consultant: ‘I should have been braver’

Letby’s trial in 2023 heard that senior paediatrician Dr Ravi Jayaram caught the serial killer “virtually red-handed” after an incident in a nursery room at the hospital in February 2016.

Addressing that incident while giving evidence at the inquiry, Dr Jayaram said he had walked into the nursery after feeling “significant discomfort” that Letby was alone with Child K.

Read more from Sky News:
Letby defence calls for miscarriage of justice investigation
Letby interviewed in prison over more baby deaths

After walking in, he said he saw “a baby clearly deteriorating” and the child’s endotracheal tube (ET) dislodged. Despite his concern over the incident, the consultant did not tell anyone at the hospital, or the police.

Explaining why he said nothing, Dr Jayaram said: “It’s the fear of not being believed. It’s the fear of ridicule. It’s the fear of accusations of bullying.

“I should have been braver and should have had more courage because it was not just an isolated thing. There was already a lot of other information.”

Hospital boss: ‘I should’ve done better’

Tony Chambers, the former chief executive of the Countess of Chester Hospital, was a key witness to give evidence during the inquiry.

During his evidence, Mr Chambers offered an apology to the families who had fallen victim to Letby and said his language had been “clumsy” in telling the killer nurse the hospital had “her back”.

“I absolutely acknowledged that we hadn’t got that right. We could have done better, we should have done better. I should have done better,” he said.

When pressed on if he tried to “stall and obstruct the police being called or this being made public”, he added: “Had that been what I had done then it would be. But I think it’s an outrageous statement and I do not believe it represents my actions.”

Jeremy Hunt: ‘Terrible tragedy happened on my watch’

Jeremy Hunt appeared at the inquiry in January where he apologised to the victims’ families, saying he was sorry “for anything that didn’t happen that could potentially have prevented such an appalling crime”.

Mr Hunt was health secretary at the time Letby committed her crimes in 2015 and 2016.

The MP told the inquiry the former nurse’s crimes were “a terrible tragedy” which “happened on my watch” and “although he doesn’t bear direct personal responsibility for everything that happens in every ward in the NHS” he does have “ultimate responsibility for the NHS”.

He recommended that medical examiners should be trained to see the signs or patterns of malicious harm in the work of a healthcare professional.