This is the selfie Alexander Palmer took shortly after killing dog walker Peter Wrighton in woodland near East Harling.

Eastern Daily Press: Killer Alexander Palmer. Photo: Norfolk ConstabularyKiller Alexander Palmer. Photo: Norfolk Constabulary (Image: Norfolk Constabulary)

Mr Wrighton, 83, from Banham, was stabbed repeatedly to the back of his head and neck and through his left eye in an attack which left his head almost severed from his body.

A jury took less than an hour on Wednesday to find former soldier Palmer, 24, guilty of murdering Mr Wrighton as he walked his dogs on August 5 last year. And today he was jailed for life with a minimum term of 28 years.

Following the verdict police released a selfie which Palmer had taken shortly after killing Mr Wrighton. Another person's face is obscured in it.

The trial at Nottingham Crown Court heard that before the killing, Palmer, of Freesia Way, Cringleford had made notes referring to voices in his head about killing people with knives.

Eastern Daily Press: A post-mortem examination revealed Peter Wrighton died from multiple stab wounds. Picture: SUPPLIED BY FAMILYA post-mortem examination revealed Peter Wrighton died from multiple stab wounds. Picture: SUPPLIED BY FAMILY (Image: Archant)

Palmer suffered mental health problems after being attacked by fellow soldiers on a night out in Plymouth in 2013.

He had serious head injuries from the attack and quit the army in 2015.

After that he experienced hallucinations with voices in his head, which Palmer dubbed Alex or Little Alex.

Police were called to woodland near the Fiveways Junction at about 10.45am on August 5 last year.

Eastern Daily Press: Police conduct anniversary checks near the scene of the murder of Peter Wrighton in East Harling, Norfolk.Picture: Nick ButcherPolice conduct anniversary checks near the scene of the murder of Peter Wrighton in East Harling, Norfolk.Picture: Nick Butcher (Image: Archant © 2017)

The death was initially treated as unexplained with police later admitting an animal attack was considered as one of the possible causes.

But a murder inquiry was launched two days later after a post-mortem examination found the victim appeared to have been 'subjected to a serious assault' with multiple stab wounds to his head and neck.

More than 100 officers were involved in the hunt for the killer as part of a massive operation which resulted in officers receiving hundreds of calls.

Palmer, formerly of Old Buckenham, was arrested a week after the discovery of Mr Wrighton's body.

Eastern Daily Press: Efit of Alexander Palmer (l) and (r) his photo from police custody. Photo: Norfolk ConstabularyEfit of Alexander Palmer (l) and (r) his photo from police custody. Photo: Norfolk Constabulary (Image: Norfolk Constabulary)

The arrest prompted searches at a number of addresses across Norfolk, including Freesia Way, Cringleford and another in Bawdeswell, where he was arrested.

Eastern Daily Press: CCTV image of Peter Wrighton at Kenninghall Post OfficeCCTV image of Peter Wrighton at Kenninghall Post Office (Image: Archant)