Four healthcare professionals have been arrested on suspicion of poisoning, mistreating and neglecting patients at a Blackpool hospital stroke unit.
On Wednesday, three women and one man were held on suspicion of administering any poison or noxious thing with the intent to injure and ill treatment or wilful neglect at Blackpool Victoria Hospital.
They are now in custody, Lancashire Police said.
It comes after Blackpool Teaching Hospitals NHS Foundation Trust contacted police last November over concerns about patient care.
In January, detectives confirmed a murder probe was ongoing after a woman in her 70s died on the stroke unit in November. Officers said they were treating it as a separate investigation.
“Given the number of arrests and the nature of the allegations, it remains a complex and sensitive inquiry”
A total of seven people have now been arrested, including a woman held in November and a man and woman arrested the following month. They have since been released under investigation.
The three people arrested last year had been suspended as part of safeguarding procedures, while the four new arrests were suspended in December, the force said.
“A number of post-mortem examinations have been conducted as part of police inquiries,” Lancashire Police said in a statement.
Det Chief Insp Jill Johnston said: “I understand further arrests could be concerning but I would like to reassure people we have a dedicated team of detectives working on this investigation.
“Our priority and the priority of Blackpool Teaching Hospitals NHS Foundation Trust is to ensure the safety of patients.
“Given the number of arrests and the nature of the allegations, it remains a complex and sensitive inquiry.
“No timescales have been set and I would ask people to remain patient while we continue to conduct our enquiries.”
Officers are supporting the families of patients who may have been involved.
“We are working closely with the Trust as well as HM Coroner for Blackpool and Fylde as part of the investigation,” Johnston added.
Anyone with information can contact police on 101 quoting log reference 0553 of November 14.