Police are trying to establish whether a university graduate found dead in a burning car knew her killer.
Catherine Wells-Burr, 23, was discovered in her red Ford Focus in a field by the side of a road.
Firefighters were alerted to the blazing vehicle shortly before 6.30am on Wednesday off the A358 in Ashill, near Ilminster, Somerset.
The car was found abandoned in a field.
Fire crews extinguished the flames and discovered the body of the Bath Spa University graduate inside the wreckage.
Avon and Somerset detectives have confirmed they are treating her "tragic and brutal" death as suspicious.
One of the theories police are working on is that Miss Wells-Burr knew her killer but officers are not ruling out a random attack.
Police are exploring the possibility that Catherine Wells Burr knew her killer
On August 25, Miss Wells-Burr updated the cover photo on her Facebook profile with a picture of a woman covering her face with a book.
Accompanying the picture was the post: "You can't start the next chapter of your life if you keep re-reading the last one."
Detective Chief Inspector Simon Crisp, who is leading the investigation, said: "This is a tragic and brutal incident in which a young woman has needlessly lost her life.
"We are working to establish what happened in the early hours of yesterday morning that led to this car being set ablaze.
"I am making a double appeal today. Firstly for those people that may have witnessed Catherine and her red Ford Focus arriving at the scene which is alongside the A358 near Ilminster.
"Did anybody see that car arrive? Did anybody see suspicious people arrive or leave the scene at about 6am to 6.30am on a busy road? We need you to call us.
"The second part of the appeal is to help us understand Catherine's private and social life.
"Did she know her killer is the question that we're asking ourselves. Did she arrange to meet somebody at the location where she met her death? These are the things we are seriously considering.
"Please don't leave it to others to tell us, call us immediately.
"The post mortem examination is yet to take place so I am unable to confirm whether she died in the fire or beforehand.
"I believe we are still searching for the offenders. At this moment there is not a specific person we are looking for.
"There are many lines of inquiry that we are examining; one of those is that this may not have been a random attack and that Catherine knew her killers or killer.
"I can assure you we will find those responsible and bring them to justice."
Tributes were paid to Miss Wells-Burr, who lived in the town of Chard with her family, and achieved a first-class degree in business management.
Maurice Hicks, head teacher of Holyrood Academy in Chard where Miss Wells-Burr was a former pupil, spoke of his shock at the news.
"Everyone at Holyrood Academy is deeply saddened and shocked to hear the news about Catherine," he said.
"She is warmly remembered as a very friendly young person, gregarious and with a great sense of humour.
"Catherine always had a smile and a positive outlook. She was very popular with the other students and had lots of friends.
"Our sincere condolences go to her family and friends at this difficult time."
Miss Wells-Burr worked as a business analyst for Chard-based Numatic International Ltd, which is best known for manufacturing Henry hoovers.
The firm was directing all inquiries to Avon and Somerset Police.