A 22-year-old man wanted in connection with the suspected murder of a teenager has handed himself in to police.
Hertfordshire Police said Jack Wall was arrested by officers investigating the disappearance of Amelia Arnold, who was last seen on Wednesday.
Detectives fear that Miss Arnold, aged 19, has been murdered and are focusing their enquiries on her home in Hadrian's Walk, Stevenage.
Wall, also of Stevenage, has been arrested on suspicion of Miss Arnold's murder.
He presented himself to officers at a police station in Hertfordshire after detectives appealed for him to contact them.
Detective Chief Inspector Tim Redfearn, from the joint Bedfordshire, Cambridgeshire and Hertfordshire Major Crime Unit, said: "Amelia's family are extremely distraught and are desperate for information on her whereabouts."
Officers particularly want to hear from anyone who lives in and around Hollybush Lane, Welwyn Garden City, and saw a white van or anyone depositing items in the area on Thursday afternoon or evening.
"I'd also renew my appeal for anyone who saw or heard any suspicious activity in Hadrian's Walk between Wednesday and Friday to come forward," added DCI Redfearn.
Meanwhile, police are continuing to question a 41-year-old man arrested on Saturday.
Anyone with information which could assist the investigation is asked to contact police on the non-emergency number 101, or call Crimestoppers anonymously on 0800 555 111.