A woman in her 90s died a week after reportedly being assaulted at a care home with a walking stick.
May Miller suffered a bleed to the head at Beech House residential home in Halesworth, Suffolk, on 9 February.
She was taken to hospital but died a week later. Police are treating her death as "unexplained".
A Suffolk Police spokeswoman said: "The cause of death will be established by a Home Office post-mortem [examination], which is to be conducted this week."
The Partnership in Care, which runs Beech House, said it was "extremely saddened and shocked by this tragedy".
"The safety of everyone within our home is of paramount importance to us and we would like to offer our reassurances to staff, residents and their families that we are fully supportive of the ongoing investigation," it said in a statement.
A spokeswoman for the Care Quality Commission said it was "aware of an incident" at Beech House but could not comment further because of the police investigation.
A county council spokeswoman said the authority had "met with home managers to receive assurances that safeguarding procedures are in place".