Police search Lucy Letby's home, where a number of key items of evidence were recovered (Image: PA)

Investigators delved into records, messages, diaries, social media activity, and more as they hunted for evidence to show who was responsible for a series of attacks on babies at the Countess of Chester Hospital.

Lucy Letby's diary and a handwritten note shown to the court (Image: Cheshire Constabulary/CPS)

Lucy Letby, who grew up in Hereford, has today been convicted of seven counts of murder and seven of attempted murder, making her the most highly convicted child serial killer in UK legal history.

Here, the CPS has detailed the key evidence used to establish Letby's guilt.

Medical records

These were crucial to establish the condition of the babies when they were attacked. When some babies recovered, the speed of their recovery was too sudden to be seen as a natural occurrence.

This Ibiza carrier bag found by police in Lucy Letby's bedroom at Westbourne Road, Chester, and contained a number of hospital shift handover sheets and her NHS nursing badge, and was shown in court during trial. (Image: Cheshire Constabulary/CPS)

Several medical documents featured falsified notes made by Letby to hide her involvement. She amended timings on several documents in an attempt to distance herself from incidents where babies had suddenly become severely unwell.

READ MORE: 

• Lucy Letby: verdicts announced in murder trial
• Lucy Letby: key dates in murder investigation

Text messages and social media activity

These were an important part of the case as they coincided with the attacks happening on the neonatal Unit. They were dated and timed, sometimes they were similar to a live blogging of events.

A sympathy card sent by Lucy Letby to parents of a child involved in the case. She took a photograph on her mobile phone of the card ahead of the youngster's funeral (Image: Cheshire Constabulary/CPS)

They also explained how Letby deceived her colleagues into believing that these inexplicable collapses were simply a natural worsening of children’s underlying conditions. They also revealed an intrusive curiosity about the parents of babies she had harmed.

Handwritten notes and diaries 

Many handwritten notes were discovered by police during their investigation.

A handwritten note written by Lucy Letby (Image: Cheshire Constabulary/CPS)

They included phrases such as: “I killed them on purpose because I’m not good enough to care for them”; “I am evil I did this”; and “today is your birthday and you are not here and I am so sorry for that”.

These notes gave an insight into her mindset following her attacks.

Staff rotas

The CPS was able to show the jury that Letby was the one common denominator in the series of deaths and sudden collapses on the neonatal unit.

A cot where Child G in the Lucy Letby court case was being treated when she projectile vomited. The black circles denote where the vomit landed. (Image: Cheshire Constabulary/CPS)

They were also able to show the jury that many of the earlier incidents occurred overnight, but when Letby was put onto day shifts, the collapses and deaths began occurring in the day.

Lucy Letby's diary (Image: Cheshire Constabulary/CPS)

The CPS was able to corroborate this further using Letby’s personal diary in which she had noted her shift patterns.