Staffordshire Police is to be investigated over contact officers had with a woman who was later stabbed at her home, a watchdog said.
Kerry Ann Day, 41, was stabbed on 25 April at Astbury Court, in Burslem, Stoke-on-Trent.
Anthony Lawton, of the same address, has been charged with her murder, the Independent Police Complaints Commission (IPCC) said.
Officers went to the address the day before her death, the spokesman said.
'Previous police contact'
Len Jackson, IPCC Commissioner said: "This is a very sad incident and I extend my sincere condolences to Ms Day's family and friends at this difficult time.
"In view of the prior contact Staffordshire Police have had at the address, I feel it appropriate to carry out an independent investigation."
There had been previous police contact at the address including attendance by police officers to an incident there the day before Ms Day's death, the IPCC said in a statement.
Staffordshire Police referred the incident to the IPCC on 7 May and following an assessment an independent investigation has begun.
Mr Lawton is due to appear at Stafford Crown Court on 5 July.