A 32-year-old woman has been arrested in connection with the murder of Catherine Wells-Burr, whose body was found in a burning car.
The 23-year-old from Chard, Somerset, was discovered in a red Ford Focus in a lane on the A358 near Ilminster yesterday morning.
Two men who were arrested have been released without charge.
Avon and Somerset detectives say the woman was arrested last night on suspicion of murder and currently remains in police custody.
Police were called to the vehicle at 6.30am on Wednesday after drivers spotted the blazing wreckage off the A358.
Firefighters extinguished the inferno and discovered the body of the Bath Spa University graduate inside the car.
Detective Chief Inspector Simon Crisp said: "A post mortem will begin today to try and identify how Catherine died.
"We still need information from members of the public and those people who knew Catherine or knew of her. It is imperative we get a full picture of her life and you may have information that could help."
Anyone with information is asked to call police on 101 or call Crimestoppers on 0800 555 111.