The new report goes beyond the embolism question Dr Lee has spoken out on previously. BBC News has only seen a summary as a full copy has not been made publicly available.
On Tuesday, Dr Lee said the panel believed all of Letby’s victims actually died of natural causes or because of poor medical care.
“There was no medical evidence to support malfeasance causing death or injury,” he told a news conference, before listing what he alleged were a number of wider failings at the Countess of Chester Hospital’s neonatal unit where Letby worked.
The report deals with the cases of all 14 babies in turn.
In one case in which Letby was convicted of killing a baby by injecting air into its stomach, the panel said their analysis indicated a cause of death arising from natural respiratory complications and chronic lung disease.
Additionally, they said doctors had failed to detect a bacterial illness and should have prescribed antibiotics.
In a case where Letby was convicted of attacking a baby by removing a tube which was allowing the infant to breathe, Dr Lee said the panel’s analysis suggests the infant collapsed because it was fitted with the wrong size tube in the first place by a consultant who “didn’t know what he was doing”.
There are similar findings for all Letby’s victims: the panel said all the deaths could be explained by natural causes or medical errors.
However, the criminal case against Letby did not exclusively rely on medical evidence.
Prosecutors also pointed to data showing she was on shift when babies fell ill, as well as circumstantial evidence – including the fact she repeatedly researched the families of the deceased and kept records which a judge said were “morbid records” of her crimes.
Speaking at Tuesday’s news conference, Mark McDonald – the barrister leading Letby’s defence – argued the circumstantial evidence was of “lesser” importance in the case against the nurse compared to the medical evidence.