Marcus Coates, who has links to the London and Kent areas, was last seen in Bristol after he absconded from HMP Leyhill in Gloucestershire.
Police are urging the public not to approach Coates, but to call 999 if they spot him.
A spokesperson for Avon and Somerset Police said: “We’re asking the public to call us if they see Marcus Coates who absconded from HMP Leyhill.
“Coates, 54, was jailed in 2012 following a manslaughter conviction.
“He’s described as white, male, about 5ft 10ins, with blue eyes and receding mousey brown hair. He has several tattoos, including his name and a rose on his name on left hand, a heart and West Ham FC on his right arm and a female’s name across his knuckles on his right hand.
“He was last seen near Bristol Bus Station between 8.30-9.30am on Thursday 28 October wearing a blue polo shirt, blue jacket, blue jeans and grey Puma trainers, as per the CCTV image.