Lucy Letby's trial heard Monday that her colleague thought "Oh no, not again" when she saw a premature baby girl collapse 28 hours after her twin brother's death.

In 2015, nurse A at the Countess of Chester Hospital had been trying to resuscitate Baby A along with other staff members when she felt his final heartbeat, reported Daily Mail. The next day, at about 12.30 a.m. on June 10, 2015, Letby, the friend she had once mentored as a student, called her over to the incubator of Baby B.

Letby, a 32-year-old nurse, is accused of injecting air into the bloodstream of the newborn, Child A, shortly after she came on shift on June 8, 2015. It was just over 24 hours after his premature birth. The 32-year-old alleged baby killer is said to have used the same method to attack his sister, Child B, on the following night shift.

Letby's colleague told the jury at Manchester Crown Court that the former "went over to her.' The nurse recalled Letby standing with her, "checking the medication." She shared that Letby said, "She's apnoeic, she's not breathing." She asked her colleague to "go and help."

The nurse said that the baby girl suddenly looked very ill and "looked very like her brother had done the night before." She described that baby as being "pale, white, with this purple, blotchy discoloration." She shared, "I just remember thinking 'Oh no, not again.'"

Nurse A, whose name was not revealed for legal reasons, summoned two doctors to help revive the child. The witness said that a breathing tube was inserted and the girl "started to stabilise quite quickly." The nurse said that she could not remember who administered intravenous fluids to Child A shortly before his collapse. But she accepted that she told police that another nursing colleague had "pressed start" in the process. Letby had assisted with checks.

According to The Sun, Letby allegedly killed seven babies and tried to murder 10 others when she was working on the neo-natal ward at the Countess of Chester Hospital. She has denied 22 charges connected to the killings that happened in 2015 and 2016.

Meanwhile, BBC reported that a line of gas in front of the spine was an "unusual finding" on the post-mortem X-ray of an infant, who was allegedly killed by Letby. During her trial, paediatric radiologist Dr Owen Arthurs said that its appearance was "consistent with, but not diagnostic, of air having been administered." Jurors were told that Dr Arthurs had been instructed to review X-rays taken of Child A, when alive and after demise, as well as other babies in the probe.

Looking at one of the post-mortem X-rays, the professor of radiology at London's Great Ormond Street Hospital highlighted to the court there was gas within the bowel and the heart. Prosecutor Nick Johnson QC asked if there was anything unusual about the X-ray, and Dr Arthurs replied, "You can also see a line of gas just in front of the spine. That is an unusual finding." The medical expert said that such a photo would not be seen in deaths by natural causes, but had been documented in cases of sepsis infection and road traffic accidents.

This is a representational image. Hu Chen/Unsplash