Thames Valley Police is appealing for help in tracing Edward Cawley, known as Ned.
The 21 year old was last seen on Tuesday (19/1).
He was serving a sentence for burglary.
Cawley is described as white, approximately 5ft 7ins tall, of thin build, with short, ginger hair, blue eyes and has an Irish accent.
He also has a tattoo on his right hand of the name ‘Chantelle’ and a scar on his left hand.
He is known to frequent Luton, Dunstable, West Bromwich, South Glamorgan and Cardiff.
PC Maureen Moore, based at Aylesbury police station, said: “We are appealing for the public’s help in locating Cawley.
“If you see him, please do not approach him but call 999 instead.
“Anyone who has any information can call Thames Valley Police on the non-emergency number 101, quoting reference number 43210025085.
“Alternatively if you wish to remain anonymous, you can contact the independent charity Crimestoppers on 0800 555 111.”