A former army commando has been jailed for life with a minimum term of 28 years for the 'callous and planned' murder of dog walker Peter Wrighton.

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)

After an eight day trial, a jury at Nottingham Crown Court took less than an hour to convict the 24-year old from Cringleford over the knife attack at East Harling last summer.

Mr Wrighton's body was discovered on The Heath on August 5. The 83-year old suffered around 44 stab wounds to the neck and head.

Palmer, of Freesia Way, who served with the British Army between 2010 and 2015, denied the attack.

The trial heard that before the killing, Palmer had made notes referring to voices in his head and killing people with knives.

Eastern Daily Press: Alexander Palmer took this selfie shortly after killing Peter Wrighton. Photo: Norfolk ConstabularyAlexander Palmer took this selfie shortly after killing Peter Wrighton. Photo: Norfolk Constabulary (Image: Norfolk Constabulary)

The hallucinations and voices in his head, which Palmer dubbed Alex or Little Alex, began after Palmer was attacked by fellow soldiers on a night out in Plymouth in 2013.

He sustained serious head injuries and quit the army in 2015.

Mr Wrighton's death was initially treated as unexplained as police began working on a theory he had been the victim of an animal attack, possibly by his own dogs.

But a murder inquiry was launched two days later after a post mortem examination found he had been 'subjected to a serious assault' with a knife.

Palmer was arrested after an anonymous tip off from a psychologist at RAF Marham, who called police after seeing media reports of what had happened on The Heath and suggesting they look at Palmer.

At RAF Marham, Palmer had told mental health professionals the voice in his head told him to kill people by attacking the throat and he seemed to have a particular grudge against dog walkers.

Prosecution barrister Stephen Spence told the court aggravating features included 'a significant degree of planning' and the fact Mr Wrighton was 'particularly vulnerable because of his age'.

'He was targeted as a relatively frail elderly man,' he said.

In mitigation, David Spens QC said Palmer was clearly 'suffering a mental disorder at the time'

'There is plenty of evidence he was psychotic,' he told the court.

'There is a history of it. He is in Rampton [secure hospital] at the moment prescribed anti psychotic medication. His full diagnosis is yet to be undertaken.

'At the time of the killing he was not taking anti psychotic medication. The side effects were deeply unpleasant and persistent.

'But for the assault on him by a fellow trainee commando back in March 2013, which would appear to have precipitated the onset of his mental disorder, you may think this offence might not have been contemplated.

'There isn't any evidence of any aggressive conduct of this kind previously. He was of positive good character.

'He managed to qualify at a young age as a commando gunner in the artillery. Very few candidates pass that course each year and he was one of 20 people that year who managed to qualify.

'That is quite an achievement and shows he had a lot of potential which now won't be realised.'

Jailing Palmer for life, The Honourable Mr Justice Goose called him a 'highly dangerous man'.

'You had stopped taking your medication, knowing that it caused an increase in your hallucinations,' he said.

'You planned this murder having bought the knife and travelled to the scene to pick on a member of the public who was walking his dogs.

'You had thought where to go, how you would carry it out and how you would leave the scene, disposing of the evidence to connect you with the attack.

'This was a callous and planned killing.'