As Lucy Letby is found guilty of murdering seven babies and attempting to kill a further six more, here's a look at how events at the Countess of Chester Hospital's neonatal unit unfolded.
In January 2012, after graduating, she was given a full time role on the neonatal ward where she was known as a trusted colleague.
Lucy Letby completes a specialist training course, which means she is one of very few staff on the ward qualified to care for the sickest babies in the high-dependency and intensive care nurseries.
Lucy Letby murders Baby A, a twin, by injecting air into his bloodstream, less than an hour after she is made his designated nurse.
Doctors say the baby boy was in a good condition and was breathing "in air" without extra oxygen help and being given expressed breast milk.
After a 30-minute handover, at 8pm Letby becomes the designated nurse for Baby A.
At 8:26pm she calls a doctor to the baby’s incubator and the on-call consultant is also alerted.
Both doctor and consultant note an "odd discolouration" on the boy's skin, patches of pink over blue skin that appear and disappear.
Despite resuscitation attempts, Baby A dies at 8:58pm.
Lucy Letby tries to kill the twin sister of Baby A when her parents are persuaded to get some rest after keeping vigil by her bedside following the death of her brother.
Her collapse comes just 27 hours after Baby A's death. She stopped breathing at around 12:30am and looked "as her brother had done, pale white and with this purple blotched discolouration", her designated nurse told the court.
An on-call registrar, Dr Rachel Lammy, is alerted and the baby girl recovers quickly once resuscitated.
The court heard the collapse was caused after Letby injected air into her bloodstream - the same method used to kill her brother.
Baby C dies after Lucy Letby injects air into his stomach through a nose tube.
Problems with his growth in the womb meant he was delivered at just 30 weeks, weighing less than a bag of sugar.
Doctors thought he was getting better, and his breathing support was reduced - but in the early hours of 14 June he suddenly collapses after his designated nurse leaves the room briefly.
He recovers very quickly, but just 15 minutes later collapses again - where Letby is seen at his cot side once more.
He stops breathing again, but despite a crash call, does not recover.
Just hours after child C dies, Letby searches on Facebook for the youngster's parents.
Lucy Letby murders Baby D by intentionally injecting air into her bloodstream.
The baby girl was born with a suspected infection and responded well to treatment - until she deteriorates and collapses three times in the early hours of 22 June.
Following the third collapse doctors and nurses attempted CPR for 28 minutes and give six doses of adrenaline.
The baby girl also has the same unusual rash, present on babies A and B, and a "hallmark" of some of the cases in which Letby injected air into the bloodstream of a victim.
Letby sends "many messages" to friends in the wake of baby D's death and the preceding deaths and collapses in which she suggested they could all clearly be explained as natural causes.
She later tells police she could not explain why she had searched on Facebook for baby D's parents in the aftermath of her death.
The head of the neonatal ward orders an internal review into the deaths of Babies A, C and D, and the collapse of Baby B, which all occurred within two weeks of each other.
Baby E, an identical twin boy, dies after Lucy Letby injects air into the bloodstream.
He was supposed to be born at Liverpool Women's Centre, but on the day of their birth the hospital was full so their mother was sent to the Countess of Chester.
As his mother delivers breast milk to the unit, she could hear Baby E "screaming" and sees blood coming out of his mouth.
The boy's blood loss eventually amounted to a quarter of all blood in his body, with a doctor saying he had "never seen such a huge bleed in a baby of that size".
After a number of collapses, Baby E is given CPR for 47 minutes, but doctors decide not to continue after noting he has been without oxygen for 15 minutes.
He is given to his parents to cuddle as he passes away.
Letby goes on to show a "very unusual interest" in Baby E's family, with social media searches on them two days after the youngster's death and again on numerous occasions in the following months, including on Christmas Day.
The day after murdering Baby E, Lucy Letby uses insulin for the first time to poison and attempt to murder his twin brother, Baby F.
Baby F is prescribed a TPN (total parenteral nutrition) bag of fluids and later suffers an unexpected drop in his blood sugar levels and surge in heart rate.
Checks on his insulin levels were carried out which showed "conclusive evidence" someone had given him insulin to poison him.
No other baby on the neonatal unit was prescribed insulin so Baby F could not have received the drug intended for some other child by negligence.
Lucy Letby makes her first attempt to murder Baby G, an extremely premature baby girl, by feeding her an excessive amount of milk.
Despite her size, Baby G vomits out of her cot and on to a nearby chair and the floor. She suffers a collapse and is not breathing.
She is moved back to the hospital where she was born and, after recovering quickly, is returned to Chester on 16 September.
Lucy Letby makes one more attempt to murder Baby G, again by over-feeding and injecting air into her stomach.
On the morning of 21 September, after being fed by Letby, the baby girl projectile vomits once more, and stops breathing briefly.
But she recovers by the time a junior doctor is called and stabilises herself.
Baby G has been left "severely disabled" as a result of the episodes.
Lucy Letby makes her first attempt at trying to murder Child I, a baby girl, during a day shift.
She attempts to inject air into the baby’s stomach through a nasogastric tube.
Letby tries twice more to murder Baby I, on 12 and 13 October.
In the second alleged incident, a night shift colleague recalls Letby standing in the doorway of a darkened room in the neonatal unit when she notes Baby I looks pale.
The colleague turns on the light and sees the bay "appeared to be at the point of death and was not breathing".
An expert paediatrician who reviewed Baby I’s case concluded the youngster’s deteriorations were consistent with the deliberate administration of a large amount of air into her stomach via a nasogastric tube.
The baby girl collapses in the early hours and requires chest compressions. She is successfully resuscitated and recovers to the extent she shows signs of hunger.
Child I's mother is called at home and told she and her partner needed to go to the hospital immediately.
Less than a hour later the child’s monitor alarm sounds and a colleague of Letby responds to find the nurse standing by the child’s incubator.
The nurse wanted to intervene as child I was "distressed", but Letby says she "would be able to sort it".
Baby I collapses and dies after attempts to revive her, led by a registrar, are unsuccessful.
An expert paediatrician believes on the final occasion the child has been injected with air into her bloodstream, which led to her "screaming", followed quickly by her collapse.
Letby is then said to have sent the baby girl's parents a sympathy card.
Senior doctors finally spot a pattern between baby collapses and Lucy Letby's presence.
The consultants try to raise the alarm with senior management, but no one believes anyone was deliberately harming babies.
A second review is ordered following the unexpected deaths of five babies in just over half a year, and six more suffering near deaths while on the ward.
It is referred up to senior managers, with inspectors raising concerns about staffing levels.
The report says whilst they could find "no definitive explanation for an increase in mortality rates" they had identified "significant gaps in medical and nursing rotas, poor decision-making and insufficient senior cover".
Letby is working a day shift when she attempts to murder twin boys Babies L and M.
She gives an unauthorised dose of insulin to Baby L and, and while that attack is underway, turns her attention to baby M by administering air into his circulation.
Baby M comes "close to death" after his heart rate and breathing drop dramatically without warning, but improves on the night-shift and goes on to make a speedy recovery.
The baby boy suffers a sudden lowering of his blood oxygen levels to life-threatening levels.
Unusually for such a small, premature baby he is crying and screaming, and he recovers after emergency assistance from doctors and nurses.
Independent medical experts said the baby's sudden deterioration was consistent with some kind of "inflicted injury" or him having received an injection of air.
Baby O, who is in a good condition and stable, suffers a "remarkable deterioration" as Lucy Letby begins work after returning from a holiday to Ibiza.
Letby injects his feeding tube with air, which blocks his blood supply, causing him to collapse.
A nurse asks if he should be moved into another nursery to be more closely monitored, but Letby refuses.
At around 2:40pm, after Letby gives Baby O some fluids, he suffers another drop in his oxygen levels and heart rate. He is given oxygen via a mask and intubated.
A rash is seen on Baby O, similar to those seen on other babies who died.
An hour later, the baby suddenly collapses again, he briefly stablises, but he collapses again and CPR begins.
He stablises again, but a little over an hour later CPR begins again. A decision is made to stop resuscitation 25 minutes later and he is put into his mother's arms.
A post-mortem examination found Baby O suffered a liver injury akin to a road traffic collision which experts say cannot have come from CPR.
Baby P suffers an "acute deterioration" as preparations are put in place to move him to another hospital.
But, just before the planned transfer, Lucy Letby tells a doctor: "He's not leaving alive here, is he?"
Shortly after, Baby P collapses and dies.
Hospital bosses reach the 'tipping point' and Letby is removed from the unit following the death of triplet brothers.
Nurses on the neonatal unit are also sent an email telling them as part of an external review they will be subject to 'individual clinical supervision' beginning with staff involved in many of the acute events.
It is claimed Letby has agreed to be the first to undergo the supervision.
Letby is put on administrative duties with the 'patient experience team' before starting a three-month secondment in the Risk and Patient Safety Office.
Letby attends formal review with her union rep, before taking out a grievance against the hospital for the move.
The Countess of Chester Hospital NHS Foundation Trust brings in Cheshire Police to assist with the ongoing review.
Hospital bosses issue a statement to say: "As a hospital we have taken the clinical review as far as we can.
"We have now asked for the input of Cheshire Police to seek assurances that enable us to rule out unnatural causes of death."
Letby is arrested on suspicion of eight counts of murder and six counts of attempted murder.
Her home at Arran Avenue, Hereford, is searched by police following her arrest.
She is released on bail pending further enquiries three days later.
After her arrest, the investigation is widened to include Liverpool Women's Hospital. No evidence that patients at the hospital came to any harm was found during the investigation.
Letby is arrested a second time on suspicion of eight murders and nine attempted murders.
She is bailed once more pending further enquiries.
Letby is arrested for the final time.
Letby is charged with eight counts of murder and 10 counts of attempted murder. She is denied bail and remanded in police custody.
The trial of Letby begins at Manchester Crown Court.
She pleads not guilty to seven counts of murder, and 15 counts of attempted murder relating to 10 babies.
After nine months, on 10 July 2023, the jury are sent out to consider their verdicts.
After 22 days of deliberation a jury finds Letby guilty of murdering seven newborn babies, and attempting to murder a further six more.
Want a quick and expert briefing on the biggest news stories? Listen to our latest podcasts to find out What You Need To Know...