Gavin Burnett escaped from the open prison at about 3pm on January 6 and is yet to be located.
Burnett, 35, is known to frequent Milton Keynes and Northamptonshire.
He is white, of medium build, 5ft 11ins, with brown short hair and blue eyes.
When he was last seen he was wearing a black and blue gillet, dark blue jeans and dark trainers.
Investigating officer, Det Insp James Mather said: “We are carrying out a thorough investigation to find Gavin Burnett and as part of this investigation we are appealing to the public to come forward with any information they have, no matter how insignificant they think it might be.
“If you know where Burnett is or if you see him please call police on 999.
“We do not believe Burnett poses a threat to the public, however please do not approach him instead contact police immediately.
“If you see Burnett in the Thames Valley region please quote reference 989 (6/1).
“If you see Burnett in Northamptonshire please quote reference 592 (6/1).
“If you do not want to speak directly to the police you can contact the independent charity Crimestoppers anonymously on 0800 555 111.”
Burnett was living in Northampton town centre in 2009 when he was jailed for two burglaries after leaving DNA on a screwdriver and torch.
The offences had happened only two months after his convictions for robbing security vans had been quashed. The Court of Appeal acted because two policemen who gave evidence in Burnett’s trial had been sacked in disgrace.