Nellie Mary Pickford, 89, a former resident at Parkfields residential home, in Somerset, will be dug up at midnight by officers at Glastonbury Cemetery.

Two further bodies will be exhumed in Somerset over the next month.

Detective Superintendent Trevor Simpson, who is leading the "unprecedented" operation for Avon and Somerset Police, said: "We are not talking about poisonings in the traditional sense.

"We are checking for drugs but we cannot go into details for operational reasons."

Police are also investigating the deaths of four other elderly residents at the home, in the village of Butleigh.

The home's former managers, Rachel and Leigh Baker, were originally arrested following the death of 97-year-old Lucy Cox on New Year's Day.