A 30-year-old man has been arrested on suspicion of assisting an offender in connection with the Ifield murder.
The man from London is in custody.
Detectives launched a murder investigation after the body of Janet Müller was discovered in a burning Volkswagen Jetta car in Rusper Road, Ifield, near Crawley on Friday (13 March) shortly after 2.30pm.
A man has been charged with her murder. Christopher Jeffrey-Shaw, 26, of Lakeside, Beckenham, London, is accused of killing Janet, a 21-year-old student from Eastbourne.
He has been remanded in custody to appear at Guildford Crown Court on 9 April.
Detective Chief Inspector Karen Mizzi from the Surrey and Sussex Major Crime Team said: “I am still appealing for information from anyone who may have seen Janet on Thursday night (12 March). She was last seen at Mill View Hospital, Nevill Avenue, Hove, at 10pm.
“If anyone saw her leaving the hospital or walking in the area, we need to hear from you.”
“Miss Müller was of mixed race, slim and 5ft 7in with shoulder length dark brown afro hair and brown eyes. She was wearing dark clothing.
“Also if anyone saw a Volkswagen Jetta car being driven in Rusper Road, Ifield, or in the area, on Friday (13 March) or anyone acting suspiciously in the area we need to hear from them.”
Anyone with information is urged to contact Sussex Police on 101 or email email@example.com quoting Operation Madeira or call the independent charity Crimestoppers anonymously on 0800 555111.