A 39-year-old man has been arrested on suspicion of causing death by dangerous driving after a woman died in a road crash.
The 51-year-old was riding a motorcycle when she was involved in a collision with a car near Llanon, Ceredigion, on Wednesday morning.
The road was closed for more than six hours following the incident.
Dyfed-Powys Police are appealing for information and people who can help are asked to telephone 101.
"Officers are appealing for anyone with information which might help inquiries to get in touch," said Insp Paul Bonning.
"Anyone with information can contact Pc 651 Hilton Jones from the Mid Wales Roads Policing Unit on 101.
"A 39-year-old man has now been arrested on suspicion of causing death by dangerous driving, and our investigation continues."