Lucy Letby has been convicted of murdering and harming babies. So what turned a likeable nurse into a serial killer? For the first time, Panorama hears from a family whose child died, a friend who’s stood by her and a doctor who tried to raise the alarm. Reporter Judith Moritz reveals evidence of a cover-up by hospital bosses and asks whether some babies’ lives could have been saved.

The show’s own verdict is on its page.