Police say they are increasingly concerned about the welfare of a teenage boy from Aylesbury who was last seen on April 4.
Mohammed Humza Wasim, 17, was last seen near Walton Street at midday on April 4 - almost three weeks ago.
Mohammed is Asian, approximately 5ft 8ins tall, of medium build, and with short black hair.
He was last seen wearing dark clothing and is believed to be wearing a baseball cap.
Investigating officer detective inspector Nikki Hemming said: “We are becoming increasingly concerned for Mohammed’s welfare and are appealing for help to locate him.
“If anyone has any information in relation to the whereabouts of Mohammed, please call 101, quoting reference 43190117750, or make a report online via the police website at https://news.thamesvalley.police.uk
“Alternatively, you can report anonymously to the charity Crimestoppers on 0800 555 111.”