Police have been given more time to question one of the two people arrested on suspicion of murder in connection with the disappearance of a 17-year-old girl.
Jayden Parkinson, from Oxford, has been missing for nearly two weeks and Thames Valley Police said they are keeping "an open mind" about what has happened to her.
A 22-year-old man was arrested at an address in Christchurch Road, Reading, on Thursday night.
A police spokesman said officers were granted a further 12 hours to question the man, giving them until 4.30pm.
A 17-year-old boy was also arrested after he attended a police station in Oxfordshire on Friday afternoon and remains in custody.
Jayden was last seen in the Iffley Road area of the city in mid-afternoon on December 3 and failed to return home that evening as planned.
"At this stage, we are keeping an open mind as to what has happened to Jayden," said Detective Chief Superintendent Andy Murray.
"Due to the length of time she has been missing and the fact that she has made no contact with her family or friends, we are treating her disappearance very seriously."
Jayden is white, of slim build with shoulder-length dark brown hair and brown eyes.
She was wearing light blue faded jeans, a brown hooded top with red lettering on it, a black waist-length jacket, and dark trainers when she was last seen.
It is believed she walked up the High Street through the town centre, arriving at Oxford train station at 4.07pm, where she boarded a train to Didcot. The last sighting of her is when she left Didcot train station at about 4.27pm.
Officers are also in Upton, near Didcot, in connection with the search.
Mr Murray said: "A number of lines of inquiry have led us to this area and we are asking residents if they saw any suspicious activity on Sunday night into Monday morning.
"Upton is a small area and I am hopeful someone might have seen something that they dismissed at the time but which may prove important to the investigation.
"As you can appreciate, this is a live investigation with multiple lines of inquiries and possible scenes, and we also have a suspect in custody. Some of the information we have received is in the very early stages of investigation and we have a team of detectives working tirelessly to find out Jayden's movements and where she is.
"Jayden's family are obviously aware of the developments in the investigation and a family liaison officer has been assigned to them to keep them updated. Our thoughts are with them at this difficult time."