A jury has retired to consider its conclusions into the deaths of five people who died in one of the UK’s worst mass shootings.

In a matter of minutes Jake Davison killed his mother Maxine, 51, and then shot dead three-year-old Sophie Martyn, her father, Lee, 43, Stephen Washington, 59, and Kate Shepherd, 66.

He then turned the weapon upon himself as he was confronted by an unarmed police officer on the evening of August 12 2021 in Keyham, Plymouth.

The inquest in Exeter heard the 22-year-old legally held a shotgun certificate and weapon having been obsessed with firearms from a young age due to a trait in autism of developing a “special interest”

He applied to Devon and Cornwall Police for a shotgun certificate in July 2017 saying he wanted to go clay pigeon shooting with his uncle.

As part of the application process Davison had declared his autism and Asperger’s but when police sought relevant information from his GP, the doctor declined to provide any as it was not mandatory.

The police granted the application in January 2018 to last five years.

Later that year the apprentice crane operator bought a black Weatherby pump-action shotgun which he kept at home in Biddick Drive.

Police were already aware Davison had a history of violence and knew that aged 12 he had assaulted two teachers and aged 13 had punched a pupil at the special school he attended.

Aged 17 he was involved in a domestic verbal argument with his father Mark and was also suspected of an assault outside a Tesco store in 2016.

In September 2020 Davison was captured on CCTV punching a 16-year-old boy up to nine times in a skate park and slapping their 15-year-old female friend after another boy called him a “fat c***”.

Detectives did not know he was a firearms holder and put him on the deferred charge Pathfinder scheme instead of prosecution.

It was only two months later a concerned Pathfinder worker alerted police and the shotgun and certificate were seized.

But just five weeks before the killings, they were handed back to Davison.

Witnesses to the shootings recalled seeing the smirking gunman on his rampage and dialled 999 after hearing gunshots.

Davison left Biddick Drive and walked into the nearby Linear Park and killed dogwalker Mr Washington.

Mrs Shepherd was fatally shot outside a hair salon on Henderson Place.

As two unarmed officers tried to save her life Davison returned with the shotgun nestled under his chin.

Risking his own life, Pc Zach Printer rushed towards him to try to make him surrender but Davison pulled the trigger – with his death captured on the officer’s body worn camera.

The five-week inquest heard there were multiple failures within the firearms licensing unit and staff were not using “professional curiosity” to scrutinise applications properly.

They had also not received nationally recognised training, which had been recommended in the wake of the Dunblane tragedy.

Ian Arrow, senior coroner for Plymouth and South Devon, has directed the jury to find each of Davison’s victims were unlawful killed.

“If you think that the killing was, on the balance probabilities, caused or contributed to by the fact that the perpetrator had a lawfully held shotgun you may choose to also record other matters that you find probably caused or contributed to that position,” he said.

The coroner told the jurors the law prevented them appearing to “determine any question of criminal liability on the part of a named person or any question of civil liability whatsoever”.

He said that in their findings they had to record the factual circumstances of the incident and gave them 31 areas to consider in their deliberations.

This included whether there was a failure at a national level to implement the recommendations of the Cullen report and whether there were failings within Devon and Cornwall Police’s firearms licensing unit.

They are also being asked to consider whether giving Davison the shotgun certificate was flawed and whether the process to return the weapon was carried out properly.

Mr Arrow said among the areas the jury could consider “probably caused or contributed” to the deaths were whether there were a number of failings in the firearms licensing unit, including whether it had been a failure to grant Davison a certificate and whether the force had failed by not revoking it.

“Whether, in licensing the perpetrator to have a shotgun there was a failure by Devon and Cornwall Police to protect the deceased,” he said.

“Whether any failures you might identify above were caused or contributed to by a failure of Devon and Cornwall Police to have in place adequate systems.

“Including systems for training of firearms licensing unit staff, governance of the firearms licensing unit, quality assurance of firearms licensing unit staff’s decision-making and ensure decisions were made at the correct level.”