A 37 year-old man is being questioned on suspicion of murder in the Riverside area of Cardiff.
A woman in her 30s was found seriously injured at South Morgan Place at just after 7.35am on Thursday morning.
She was pronounced dead at the scene by paramedics and her next of kin have been informed.
Detectives say the suspect - who is known to the victim - was arrested shortly afterwards on Seawall Road and remains in custody.
South Wales Police are not looking for anyone else in connection with their investigation, but they are appealing for witnesses to come forward.
Earlier, Detective Superintendent Mark O’Shea said: “Residents will notice an increased police presence in the area while we investigate. Anyone with information yet to speak to police is encouraged to get in touch.”
Nearby residents and people in or around South Morgan Place and Seawall Road are being asked to check their private CCTV or dashcam footage.
They’re also appealing to anyone who was travelling between those areas at the time - including Wellington Street, Clare Road, Penarth Road, and East Tyndall Street - but have not yet spoken with officers.
Officers said on Thursday night they were particularly keen to trace the movements of a grey Ford Fiesta car in the area at the time.
Detective Chief Inspector Matthew Davies said: “We have a dedicated team of investigators who have been carrying out extensive enquiries in the area, and I would like to thank everyone who has reached out with information so far.”
“We are appealing to anyone with CCTV, dashcam, or ring doorbell footage, or anyone else who may have seen something suspicious, to come forward.”
“Specifically, we're looking for anything involving a grey Ford Fiesta in the mentioned areas.”
Anyone with information should contact South Wales Police on 101, or visit their website, quoting reference no. 2500207506.

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