Detective Superintendent Andy Smith said: "This is a complex investigation and we are pursuing many leads".
He was found by another dog walker with his two small dogs unharmed nearby about 10.45am near East Harling, Norfolk.
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".
However officers said they still need the public's help to trace Mr Wrighton's final steps - and gave descriptions of three people they want to speak to in connection with the incident.
The former BT engineer was found unresponsive by a member of the public in woodland on Saturday, where he had gone to walk his dogs.
A man in his 20s has been arrested on suspicion of murder over the death of an elderly dog walker.
The first is described as a slim white male over 50, with pale skin and grey or white hair and balding on top.
Police said the man they have taken into custody is from the local area.
The second potential witness is a white male with a tanned complexion, aged 25 to 30, 5ft 9in to 5ft 11in, with an athletic build, short, dark wavy hair and dark eyes. It is believed he was wearing a blue t-shirt and grey floppy, gym-style shorts above the knee, and heavyduty flip-flops.
"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".
"In particular we want to be called by or about two different men who were seen in different areas close to the murder scene".
Anyone with information about the murder or any suspicious activity should contact Norfolk Police immediately on 0800 056 0944 or 0207 158 0010, quoting Operation Graduate, visit the mobile police station or alternatively contact Crimestoppers anonymously on 0800 555 111.