A man has been charged with the murder of 17-year-old Jayden Parkinson following her disappearance nearly two weeks ago, Thames Valley Police said.
Ben Blakeley, 22, of Christchurch Road, Reading, has also been charged with perverting the course of justice and will appear at Oxford Magistrates' Court this morning.
A 17-year-old boy who is being questioned on suspicion of murder remains in police custody.
Specialist search teams backed by helicopters and police dogs have been searching for any trace of the 17-year-old who has not been seen since she was spotted leaving Didcot train station, in Oxfordshire, on December 3.
Throughout the weekend, police have continued a detailed search of an area of farmland just outside the village of Upton, near Didcot, where they appear to be focusing their efforts on a small patch of woodland near the church.
The police's inquiry team has now grown to more than 100 officers and Superintendent Christian Bunt said the existing searches could continue for "days" as the force works to discover what has happened to the teenager.
In a heartfelt plea, her mother Samantha Shrewsbury posted a message on social media site Facebook saying: "My baby, my princess, my heart is so heavy, baby girl.
"I just want to see you walk through my door with a 'ta-dar'.
"I need you little lady, my heart feels so empty without you."
Mr Bunt, Oxfordshire police commander, said officers were also continuing to sift a grassy area of wasteland in the Lydalls Road area of Didcot.
Residential addresses have also been searched and a recycling bin was earlier removed for further examination.
Mr Bunt thanked the public for their help with the inquiry so far, but urged people not to carry out their own searches as these could prove a risk to the ongoing police investigation.
He added it was the complete lack of any contact or activity from Jayden - she has not used her mobile phone or bank account since going missing - that had led detectives to believe she may have been killed.
The teenager, who had recently left home in Didcot to live in Oxford, failed to return to the city on the evening of December 3, as planned.
Police have pieced together her movements in the run-up to her disappearance, and believe she walked up Oxford's High Street through the town centre, arriving at the train station at 4.07pm, where she then boarded a train to Didcot.
The very last sighting of her is when she left Didcot train station at about 4.27pm.
Detective Chief Superintendent Andy Murray said police were focused on tracing a man seen with a large suitcase in a field in the small village of Upton in the early hours of December 9.
He said: "That suitcase was large, it was heavy, it was difficult to manage and that man was having difficulty removing that suitcase from that area."
Mr Murray said the same man with the suitcase was seen in Didcot about half an hour later.
He is described as about 20, white, about 5ft 6in, of medium to slim build, with short dark hair.
The suitcase was about 3ft by 2ft, about 15in deep and light coloured, probably made of canvas material.
Mr Bunt added: "I would like to thank the public firstly as there's a huge amount of information coming in and a lot of vital lines of enquiry we are following. Please keep that information forthcoming," he said.
"We have got two significant search areas at the moment.
"We continue to focus on the area in Upton just outside of Didcot and we understand that is having a big impact on the local community.
"It's quite an extensive search area and we have got lots of officers there and we now have a fairly significant search area in the Lydalls Road area of Didcot.
"We've got a lot of resources attached to the operation, over 100 officers, specialist search and investigative officers and it's also important to mention we have specialist officers with the family supporting them."
Jayden is white, of slim build, with shoulder-length dark brown hair and brown eyes.
When last seen, she was wearing light-blue faded jeans, a brown hooded top with red lettering on it, a black waist-length jacket, and dark trainers.