KILLER nurse Lucy Letby used a chilling colour-coded system to track her gruesome crimes in a childish teddy bear diary.
The monster’s secret code was discovered after she was first arrested over the rising death rates in July 2018.
When police searched her modest home, they discovered a chilling cache of scribbled diary entries and Post-It notes.
She had also kept a treasure trove of sick mementos, including handover sheets and resuscitation notes.
Detective Inspector Rob Woods said the evil nurse’s coding system eventually helped police snare her.
He added: “The amount of material we found at her home address was, I think, a massive surprise to us when she was first arrested.
“It gave us a really good steer for the second occasion as to what sort of things we were looking for.
“So as an example, something that’s been very useful to the enquiry has been Miss Letby’s diaries.
“They appeared to be and it became clear later that it was almost a code of coloured asterisks and various other things put in a diary that marked significant events.”
The detective said Letby continued dropping hints in her writing even after she had been arrested the first time.
This stunned police, who assumed she would stop leaving the clues having cottoned on they were onto her.
DI Woods added: “It turned out when we searched that second time, she had continued to write her thoughts and all sorts of processes about the investigation about the events that she was being investigated for.”
The nurse had scribbled haunting notes in diaries and on Post-It notes, including one that read: “I am evil I did this.”
The note added: “I don’t deserve to live. I killed them on purpose because I’m not good enough to care for them.
“I am a horrible person.”
Other notes were declarations of love for a doctor colleague, who cannot be identified, that she repeatedly confided in as her death toll rose.
There were some that bore the messages “Kill me” and “Help me” along with the names of some the babies she murdered.
Letby also kept detailed handover sheets relating to 13 of the children she was either killed or hurt.
A further 99 contained information on babies she treated while she was working as a student nurse.
Her first-ever handover sheet was found in a keepsake box decorated with roses, while others had been dumped in bin bags in her garage of kept at her parents’ home.
During her trial, Letby claimed the twisted haul was simply because she “collected paper”.
But jurors were told she actually kept the notes to enable her to look up the parents of her victims after targeting their children.
Britain’s most prolific child killer murdered seven babies in a year-long reign of terror at Countess of Chester Hospital.
She also attempted to kill six others as she became a “constant malevolent presence” on the neo-natal ward.
Letby on Monday became the fourth woman ever to be handed a whole life tariff after Rose West, Joanna Dennehy and Myra Hindley, who died in 2002.
The shameless monster refused to enter court to face justice in what the families of her victims described as a “final act of wickedness from a coward”.
