Joanna Michael's family are 'completely devastated' to lose her
Two police forces are being investigated over their responses to four phone calls in the minutes before a woman was found fatally stabbed.
The body of Joanna Michael, 25, was found at a house in Crumlin Drive, St Mellons, Cardiff, on Wednesday morning.
A man, 19, remains in custody and is being questioned by South Wales Police as part of its murder inquiry.
The Independent Police Complaints Commission (IPCC) will look at actions South Wales Police and Gwent Police.
Ms Michael's family said they were "completely devastated" by her death, and called her a "wonderful mother, daughter, granddaughter, niece and cousin to all her family and a wonderful friend to so many".
In a statement, her family said: "She will be sorely missed by everyone who knew and loved her".
The IPCC said Ms Michael made two phone calls, at approximately 0230 BST and 0245 BST. Two phone calls were made by a witness.
In a statement, the commission said initial call went through to the Gwent Police control room because St Mellons is close to the border between the two force areas.
Gwent Police contacted South Wales Police, which sent officers from Rumney police station in Cardiff.
The IPCC said the South Wales Police officers arrived at Ms Michael's home approximately 20 minutes after the initial call, but after she had been fatally stabbed.
IPCC commissioner for Wales Tom Davies said: "I would like to extend my condolences to Joanna's family and friends, who was also the mother of two small children.
"The IPCC is in the process of contacting her family to explain our involvement and will also keep them informed of the progress of our investigation.
"The IPCC investigation will be carried out by our own investigation team and will focus on the police response to the emergency calls made, as well as the communication between the two police forces.
"I have also asked the investigators to look at any previous incidents at this address.
"The police murder investigation will take primacy at this stage and I would like to assure Joanna's family and the public that the IPCC will ensure that its investigation will not impede the police criminal investigation."
Anyone with any information about the incident is asked to contact the incident room in Fairwater on 101, or the independent charity Crimestoppers anonymously on 0800 555 111.