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 had been 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 focussing their inquiries on her home in Hadrian's Walk, Stevenage.
Wall, also of Hadrian's Walk, 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.
"Intelligence-led searches are taking place in the Stevenage area to find Amelia but we would appeal to anyone who can provide information of her whereabouts to contact police immediately via the non-emergency number 101."
Wall has been arrested on suspicion of Miss Arnold's murder and the investigation is currently centred around their shared home.
Police, who are continuing to question a 41-year-old man arrested yesterday, also confirmed that significant evidence had been found in an area close to Hollybush Lane, Welwyn Garden City.
Mr Redfearn added: "We believe evidence in relation to the murder has been left there and we are extremely keen to hear from anyone who lives in the area of Hollybush Lane and saw a white van or anyone depositing of items in the area on Thursday afternoon or evening to make contact with police.
"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."