A murder inquiry is under way after detectives investigating suspected poisonings on the stroke unit at Blackpool Victoria Hospital discovered one woman had suffered a "suspicious" injury.
This is what we know so far:
Valerie Kneale, 75, from Blackpool, died on the stroke unit at Blackpool Victoria Hospital on November 16. Her family has paid tribute to "the most precious wife, mother and grandmother".
Eight days earlier, hospital bosses had called in police after a "whistle blower" raised concerns about patients being mistreated on the ward.
Three nurses have so far been arrested - and bailed pending further inquiries - as part of that investigation. The first was arrested on November 9, the day after the concerns were flagged up to police. The others were arrested a month later.
Detectives ordered post mortem tests on "a number of patients" and that is how Ms Kneale's injury came to light. However, her death is being investigated separately to the ongoing poisonings inquiry.
In a statement, Lancashire Police said the cause of Ms Kneale's death had not been confirmed but it was being treated as "suspicious". No arrests have been made in relation to the murder inquiry and the nature of the injury discovered has not been revealed.
The nurses - two women and a man - arrested on suspicion of administering poison or noxious fluids as part of the initial investigation into "mistreatment and neglect" are not being linked to Ms Kneale's death.
Blackpool Victoria Hospital said it reported the initial concerns to police "immediately" and has since worked closely with police and co-operated with detectives' inquiries.
Chief executive Wendy Swift said: “We would like to reassure all our patients that all necessary actions to provide safe care will continue to be taken and the provision of hospital services will be uninterrupted.’’