
Derrick Bird - the man who killed twelve people and then killed himself in Cumbria - legally held the two guns he used in the carnage.
The fact that he was licenced to keep the shotgun and a .22 rifle has prompted calls for a tightening-up on the renewal of gun licences from some quarters.
But Lord Brian Mackenzie, formerly president of the Police Superintendents' Association and a former Chief Superintendent with Durham Constabulary, said it was not easy to decide who should have a shotgun and who should not.
He suggested that its would be impossible to creas a sysmte for checks that would contend with someone who could be "perfectly stable but then become unstable".
Lord McKensize carried out a review of gun laws following the deaths of 16 people in the 1987 Hungerford Massacre carried out by Michael Ryan.
He said although Derrick Bird's case was different from Ryan's in Hungerford, the rules might need to be looked at again.
He said "In rural communities obviously shotguns are fairly commonly used and it's very difficult, I think, to decide who should have a shotgun.
"Clearly we do need to look at the system, find out the facts in this particular case.
"There's a difference between a shotgun and a sniper rifle which this chap, Derrick Bird, seemed to have so I think we need to look at the evidence and find the facts and then we'll decide whether in fact we need to tighten the regime."
Asked if police checks on firearms licensing are mandatory and always carried out, Lord Mackenzie said: "In some places it will be rigorous and in other places perhaps it isn't done sufficiently tightly and that's something we need to look at, clearly, because the police have many demands on their time.
"It's a very complicated area, it's time consuming, but clearly it's very important when it affects people's lives."
Prime Minister David Cameron said that the UK already has some of the tightest gun laws in the world and although he promised to look at the regulations he said there would be no "knee-jerk reaction".
He is to visit Cumbria on Friday along with Home Secretary Teresa May.
It now appears clear that a row over a family will was the spark that sent Bird on his shooting rampage in West Cumbria.
The first person that the 52-year-old gunned down was his twin brother David and local solicitor, Kevin Commons.
That was the start of a three-hour massacre across rural Cumbria in which he took the lives of 12 people - most selected at random - along with 25 that he injured.
Cumbrain detectives were still trying to find-out what transformed a calm father-of-two into a homicidal maniac.
One central line of inquiry is believed to be the row that developed over the details of a will made by Bird's mother, Mary, who is seriously ill.
His killing campaign began at a taxi rank in the quiet town of Whitehaven and ended when he shot himself in woodland at a place named Boot.
Over three hours he fired on dozens of people in 30 locations armed with two weapons and more than 100 detectives will spend weeks taking statements to trace the exact route taken by Bird on his rampage.
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