Lucy Letby’s quest for freedom gained a potential boost today, as an expert suggested that a deadly bacterium might have played a role in the death of one of the infants she was accused of murdering.

Currently serving life imprisonment for the murder of seven babies and the attempted murder of seven more, Letby was found guilty of these charges, including two attempts on a single victim.

However, her defense team has unearthed evidence indicating that the same bacterium responsible for the deaths of three infants at a Glasgow hospital was also present at the Countess of Chester Hospital, where Letby was employed.

Lawyers for the 36-year-old discovered traces of Stenotrophomonas maltophilia, a bacterium found in water, in the endotracheal tube of Baby I back in February of the previous year.

This revelation follows Letby’s trial, where it was alleged that she caused the infant’s death on her fourth attempt by administering a lethal dose of air and overfeeding with milk.

Meanwhile, investigators are conducting a fatal accident inquiry at Glasgow’s Queen Elizabeth Hospital, following the deaths of three children and three adults attributed to this bacterium.

This hospital admitted that contaminated water was likely to have caused serious infections in young cancer patients after denying any connection for six years.

Now, obstetrician Dr Martyn Pitman has called for a similar line of inquiry at Countess of Chester which could prove Letby was not responsible for the deaths.

Lucy Letby is serving 15 whole-life orders after she was convicted at Manchester Crown Court 

Bodyworn camera footage issued by Cheshire Constabulary of Lucy Letby’s arrest in 2018

The defendant worked as a nurse on the neonatal unit at the Countess of Chester Hospital

An artist’s drawing of Lucy Letby giving evidence at Manchester Crown Court in June 2024

He told The Sun: ‘It is potentially hugely relevant and important – it always has been.’

It follows findings from Letby’s team that the hospital had ‘poor plumbing and drainage’ and required intensive cleaning, which could have led to the bug spreading.

Evidence suggested sewage and plumbing issues at the Countess of Chester, including ‘foul water’ in the sinks and a flood in the neonatal unit in January 2016.

Dr Pitman told the newspaper: ‘When the sewage leak was confirmed the unit should have been closed, the vulnerable babies moved out and/or transferred to other units until the issue has been sorted and cultures were negative.’

He added: ‘I feel certain that details of more infected babies across that time period will emerge.

‘A baby in the same bay as twins A and B developed awful infection symptoms and was, fortuitously, transferred to Liverpool Women’s Hospital and survived.’

He said there were ‘differing opinions’ on how likely it is that the baby was killed by the bacteria rather than Letby.

Dr Pitman was sacked in 2023 after raising whistleblowing concerns about midwifery care at the Royal Hampshire Hospital in Winchester.

Last week it was confirmed Letby will face no further charges over additional deaths and collapses of babies that were investigated by police.

A photo taken in July 2018 of Lucy Letby’s bedroom in Chester, which was shown in court

Mark McDonald is representing Letby and claims she is the victim of a miscarriage of justice

Police investigate at Lucy Letby’s home in Chester in June 2019, with a tent erected outside

Cheshire Constabulary passed additional evidence to prosecutors last year for consideration, linked to eight potential offences of attempted murder and one offence of murder at the Countess of Chester Hospital.

Another two allegations of attempted murder and murder were linked to one child at Liverpool Women’s Hospital.

In a rare step, Cheshire Constabulary spoke out publicly against the decision, which it said was ‘not the outcome that we had anticipated throughout our investigation’. 

A group of campaigners is backing Letby and has submitted reports to legal review body the Criminal Cases Review Commission to try to get her convictions overturned. 

Letby was convicted in July 2024 of the offences which were said to have happened between June 2015 and June 2016.

She was twice denied permission to appeal against her convictions in 2024.

Next Wednesday, a Netflix documentary about the investigation into Letby will feature never-before-seen footage of the nurse during her arrest and questioning.

The film – ‘The Investigation Of Lucy Letby’ – will also include new testimony from police and contributions from the mother of one of the victims. It is the first time a family member involved in the prosecution has spoken in a documentary.

Lady Justice Thirlwall’s inquiry report into how Letby was able to commit her crimes on a hospital neonatal unit is due to be published this year.