A coroner said there "may have been an opportunity to safeguard" a woman who died after a fellow care home resident attacked her with a walking stick.
May Miller, 95, died after being assaulted in her sleep by dementia patient David March, 89, at Beech House in Halesworth, Suffolk in February.
Coroner Jacqueline Devonish has raised concerns over information-sharing in a prevention of future deaths report.
Suffolk Safeguarding Partnership said a review into the case was ongoing.
An inquest in October heard Mr March, who had moved from an independent living facility five days before the attack, was "clearly hallucinating" at the time.
Ms Devonish said Ms Miller, a former school cleaner, "died from natural causes precipitated by a violent assault".
The inquest heard Mr March had no recollection of the attack on Ms Miller, and he died the following month.
In her report, Ms Devonish said "multiple investigative agencies may have been aware" of Mr March's "risk factors but that due to his not having been admitted to Beech House from a registered facility, that information-sharing was not possible".
She concluded: "Had there been in place a system for sharing safeguarding information... there may have been an opportunity to safeguard May Miller."
The Suffolk Safeguarding Partnership includes the county council, police, and healthcare services.
Its independent chairman, Anthony Douglas, said "there are clearly important lessons to be learned".
He said he was "so concerned about the circumstances of May Miller's death" that a review was commissioned to be carried out by an independent external report writer and would be published in due course.
"I want to acknowledge the family, their loss and thank them for discussing with us the need for a review," he said.
"The review will cover the coroner's findings about poor information-sharing as well as any other issues which arise from our in-depth examination of what happened to May Miller."