Jamie Frater, 43, was jailed for life in 1993 for the murder of teacher Geoffrey du Rose in Bournemouth.
He went on the run after failing to return to prison in 2012, but later gave himself up. He also absconded from open prison in 2001.
Members of the public are being advised not to approach Frater, who "could present a risk to the public".
Det Supt Jez Noyce, of Dorset Police, said: "There may be various reasons why he has not complied with his release from prison licence conditions and I appeal to him directly to make contact with police at the earliest opportunity.
"I'd like to assure members of the public that officers are making every effort to find this man as soon as possible".
Frater was convicted stabbing Mr du Rose when the teacher chased him from the garden of his home following a robbery at a nearby shop.
He is described as white, of medium build, 5ft 8ins tall, with short, receding, brown hair.
A convicted murderer missing from Dorset is wanted by police after he breached his licence conditions.