A British paediatric nurse has been charged with the murder of eight babies and the attempted murder of 10 more after a lengthy investigation that saw her arrested and released multiple times.
Lucy Letby has now been charged by Cheshire Police and will appear in court, the BBC has reported.
Suspicions were first raised in 2017, when there was a disturbing rise in deaths at the neonatal unity at the Countess of Chester Hospital, where Letby was a celebrated member of staff.
Speaking before charges were laid, Detective Chief Inspector Paul Hughes of Cheshire Police said: "In July 2018, a healthcare professional was arrested on suspicion of murder in relation to the deaths of eight babies and the attempted murder of six babies at the neonatal unit at the Countess of Chester Hospital. She was subsequently bailed pending further inquiries."
"In June 2019, the healthcare professional was re-arrested on suspicion of murder in relation to the deaths of eight babies and the attempted murder of six babies. She was also arrested in connection with the attempted murder of three additional babies.
"Today, as part of our ongoing inquiries, the healthcare professional has been re-arrested on suspicion of murder in relation to the deaths of eight babies and the attempted murder of nine babies.
"The woman is currently in custody helping officers with their inquiries."
Police first became involved in 2017, launching an investigation into the deaths of 15 babies between June 2015 and June 2016, the Daily Telegraph reported.
DCI Hughes added: "Parents of all the babies have been kept fully updated on this latest development and they are continuing to be supported throughout the process by specially trained officers.
"This is an extremely difficult time for all the families and it is important to remember that, at the heart of this, there are a number of bereaved families seeking answers as to what happened to their children."
A conviction for eight murders would make Letby Britain's worst child killer, but neighbours who spoke to media when Letby was first arrested said they were in disbelief someone so "dedicated to her job" could be accused of anything like what had been suggested.
One told the Chester Chronicle they had known her since she was just 3 years old and "she was lovely, she always has been".
Others said Letby kept to herself and didn't know too many people in the area.
After that initial 2018 arrest, several mothers wrote online of their horror that their children were cared for by Letby.
One said her daughter was cared for by her "every day for seven weeks".
Another recognised her instantly as a nurse who was involved in the care of two of her grandchildren.
In an interview with a local newspaper, Letby told why she loved nursing.
"I qualified as a children's nurse from the University of Chester in 2011 and have been working on the unit since graduating," she said.
"I also worked on the unit as a student nurse during my three years of training. My role involves caring for a wide range of babies requiring various levels of support.
"Some are here for a few days, others for many months and I enjoy seeing them progress and supporting their families."
- Additional reporting, news.com.au