A crossbow killer has been jailed for life after murdering retired lecturer Gerald Corrigan at home in North Wales in a 'medieval-style execution'.

Terence Whall, 39, was also handed a concurrent six-year sentence for conspiracy to pervert the course of justice the night he killed Mr Corrigan, 74.

The sports therapist, from Bryngwran, was convicted on Monday for shooting the pensioner outside his home in Holyhead, Anglesey.

Mr Corrigan, who had previously worked as a lecturer in photography and video, was found at around 12.35am with a crossbow bolt in his chest last April 19.

He died of his injuries one month later while being treated in hospital.

Terence Whall (pictured) has been jailed for life today after murdering retired lecturer Gerald Corrigan at home in Wales in a 'medieval-style execution'

Excalibur Micro 355 crossbow used for test firing, and shown at Mold Crown Court as Whall, 39, was found guilty of murder and for conspiracy to pervert the course of justice

Despite a parallel fraud case being investigated by police, there were no known motives for the killing of Mr Corrigan by indebted Whall.

Speaking in court from behind a screen, Mr Corrigan's son Neale said through tears: 'How can someone choose to use such a barbaric weapon on an old man?

'Did they really want to cause him a slow and painful death?

'Because that is what we witnessed and although God will ease the pain for us, we will never ever be able to forget that.'

Also reading a statement from behind a screen, Mr Corrigan's partner Marie Bailey, who suffers from multiple sclerosis, said: 'It is a terrible inferno inside me every day, thinking of how Gerry was murdered and how he suffered.'

Whall reportedly did not react when he was handed the life sentence by judge Mrs Justice Jefford at Mold Crown Court today.

The judge told Whall: 'You have deprived Mr Corrigan's family of any explanation for what was a horrific death in which Mr Corrigan was completely blameless. For your own reasons you clearly had a plan to kill.'

Mr Corrigan (pictured), who had worked as a lecturer in photography and video, was found at around 12.35am with a crossbow bolt in his chest last April. He died of his injuries one month later while being treated in hospital

She added: 'Your arrogant belief that you could get away with murder was misplaced.'

Whall had previously denied murdering the pensioner, who died one month after being shot in the chest with a crossbow bolt on April 19 last year.

He and his three co-defendants - Darren Jones, 41, Martin Roberts, 34, and Gavin Jones, 36 - also denied conspiracy to pervert the course of justice after setting alight Whall's Land Rover Discovery the night he killed Mr Corrigan.

Anna Pope, prosecuting, told the court how Whall, originally from east London, had hidden behind a wall outside the pensioner's remote home and tampered with the satellite dish to lure him into the garden where he shot him.

Whall initially claimed he was at home in Bryngwran on the night of the shooting.

He later claimed that he was engaged in a sexual encounter with friend Barry Williams, who denied the claims, in a nearby field after the GPS device from his Land Rover Discovery was recovered.

Police said a parallel fraud investigation was ongoing after claims Mr Corrigan and Ms Bailey handed over £250,000 to convicted fraudster Richard Wyn Lewis.

The court heard how Whall had hidden behind a wall outside the pensioner's remote Holyhead, Anglesey home (pictured) and tampered with the satellite dish to lure him into the garden

Ms Pope said Whall, who was heavily in debt, had given no motive for the killing. She said there was no evidence of a connection between him and Mr Corrigan.

Though the prosecution argued that Whall had been paid to carry out the murder, or had killed Mr Corrigan for fear of being reported for fraud, Judge Jefford told the court it was 'speculation' to say the shooting was a 'murder for gain'.

Earlier in proceedings, the prosecution argued that the reasons for Whall's crime may forever remain shrouded in mystery.

After Whall's Land Rover was discovered burnt out in a disused quarry last June, he was handed a concurrent six-year sentence for perversion of justice.

Gavin Jones was jailed for five years for conspiracy to pervert the course of justice, and the judge said he was 'integrally involved' in the plan.

His brother Darren Jones was sentenced to two years and 10 months for arson, and Roberts was jailed for two years and four months for arson.