The other, aged 30 to 50, was wearing dark clothing and seen walking without a dog to the north of the heathland where Mr Wrighton had been walking.
Det Supt Andy Smith said at the time: 'We want to piece together Peter's final days so that we can understand what happened to him and why.
The victim's two dogs stayed by his body until it was found by a passer-by among thick nettles and undergrowth.
On Thursday, police released footage of Mr Wrighton shopping in a post office on the day that he died along with maps of his final movements in the hope that it would "jog memories".
More than two hundred people have already come forward to help in the police inquiry but officers are still trying to trace key witnesses. He was seen walking without a dog in the northern area of the heath.
Elizabeth Truss said: "I am deeply shocked and saddened by reports of the death of local man in woodland near East Harling".More news: U.S. airstrikes in Afghanistan are said to kill 16 civilians
Norfolk's County Policing Commander, Chief Superintendent Mike Fawcett, said: "It's unusual to have an attack where we can't show if there's any connection between the victim and the offender, and we don't know the motive for the attack".
■ White man with a tanned complexion, aged 25 to 30 years old, between 5ft 9in and 5ft 11in tall.
He wore a grey or blue t-shirt, grey floppy gym-style shorts above the knee and heavy duty flip flops, and was seen within the boundary of the woodland site which police are searching. He is of athletic build with short dark wavy hair and dark eyes.
He added search teams were using metal detectors and dogs to hunt for clues, and that more than 100 officers were working on the case.
"As part of our comprehensive enquiries, we are now in a position to appeal directly to a number of people who may be able to provide us with information that could be vital".
Anyone with any information should call The Operation Graduate helplines on 0800 056 0944 or 0207 158 0010.