A man has been arrested following the death of a 93-year-old woman at a nursing home, police have said.
The 54-year-old suspect, from Weybridge, Surrey, was held on suspicion of manslaughter by gross negligence.
The victim died at the Royal Berkshire Hospital in February after suffering burns at Birdsgrove Nursing Home in Bracknell, Berkshire.
Two others - a man aged 43 and a 19-year-old woman - were arrested in February on suspicion of ill treatment or wilful neglect of a person without capacity under the Mental Capacity Act 2005.
Both are on police bail, Thames Valley Police said.
Detective Inspector Dave Hubbard, of the force's major crime team, said Wednesday's arrest was likely to cause concerns for residents and relatives.
He said: "Our priorities at this time are to conduct a thorough investigation in a sensitive manner so as to minimise disruption and distress for those involved, and to protect other residents of the home and those involved in proceedings.
"The most important thing is that we establish the exact circumstances surrounding this woman's death for her and for her family, and ensure that there is safeguarding in place for the future."
Birdsgrove is registered to provide care for up to 87 people. Following its latest inspection, the Care Quality Commission (CQC) gave Birdsgrove an overall rating of inadequate in October.