Allegations of neglect at two Berkshire nursing homes are being investigated, police have said.
Concerns were raised about The Berkshire in Barkham Road and Woodbury House in Jouldings Lane with Wokingham Borough Council.
Operator BrighterKind said it was co-operating with police over what it called "historical concerns" of one person.
Thames Valley Police said residents' next of kin had been informed.
Det Con Nathan Adby, said: "Officers are currently conducting inquiries following concerns about people who are, or who have been, a resident at either The Berkshire or Woodbury House."
Robert Mitchell, from BrighterKind, said it was "important to emphasise police have not said they have found anything to indicate any instance of neglect".
"The wellbeing of our residents is our first consideration and we actively encourage people to raise any concerns that they have about any aspect of care," he added.