Colleagues of serial killer nurse Lucy Letby have continued to insist that she is innocent after the baby murderer was jailed for life earlier this week.   Nurses who worked alongside Letby, 33, at the Countess of Chester hospital are reportedly struggling to accept that she murdered seven babies and tried to kill another six.   Jurors listened to ten months of evidence that linked Letby to the deaths, which saw youngsters injected with air, poisoned with insulin, and overfed …