Police have warned the public not to approach Wayne Jones, who is an inmate at HMP North Sea Camp.
The 39-year-old fled the Category D open prison on Sunday evening.
“We are warning the public not to approach a man who has absconded from prison,” said a spokesperson for Lincolnshire Police.
“He is described as 5ft 7in tall, of small build, with brown hair and brown eyes. He has a scar under his left eye and a tattoo on his left wrist.”
Jones is serving a life sentence for rape.
The police have urged anyone who sees the prisoner not to approach him, but instead call Lincolnshire Police on 999 or contact the force by email.
In July, the governor of HMP North Sea Camp was criticised for calling inmates “residents” as part of the open prison’s “rehabilitative culture”.
The POA, the prison officers’ union, said the move was “ill thought-out”. But the Independent Monitoring Board (IMB) said the prison had managed to create “a polite and calm atmosphere”.
Prisoners serving life sentences can only be moved to a Category D prison if Her Majesty’s Prison Service decides they are not a danger to the public or likely to abscond.
The transfer can be a precursor to an inmate’s eventual release from prison, and they are often permitted to leave the premises for limited periods of time.
“We have argued for 10 years that the system used by the prison service to determine whether an inmate can be moved to an open prison is not fit for purpose,” Glyn Travis, spokesman for the POA, told The Independent.
Mr Travis called the evaluation process a flawed “tick box exercise”.
Members of the public can report sightings of Jones by email to force.controllincs.pnn.police.uk with incident 367 in the subject line.