A sixth person has been arrested in London over the fatal shooting of a female police officer in Bradford.
Pc Beshenivsky had three children and two step-children
The man - along with four other men and one woman who were arrested on Saturday - are being questioned in London over the murder of Pc Sharon Beshenivsky.
The 38-year-old mother-of-five was shot in the chest on Friday after being called to a robbery at a travel agents.
Her colleague, Pc Teresa Milburn, 37, was also shot and is being treated in hospital for a shoulder injury.
Her injury is described as non life-threatening.
Both women were probationers with less than two years service.
Pc Milburn is in hospital with a shoulder injury
The former head of the Metropolitan Police, Lord Stevens, said the double shooting had convinced him the death penalty should be reinstated for police killers.
He told the News of the World: "For the first time in my life, despite 40 years at the sharp end of policing, I finally see no alternative.
"Such an extreme act of pure evil can only be met by the most extreme of responses - and that can only be death."
Giving more details of the raid, Det Supt Andy Brennan said that shortly after 1500 GMT on Friday three men entered the travel agents in Morley Street to make inquiries about purchasing tickets. They had at least one gun and a knife.
He said the three men jumped over the counter and one member of staff was struck with a firearm across the head.
He was taken to hospital and was said to be in a "comfortable" condition.
Members of staff were tied up by the raiders and a quantity of cash was stolen, but it is not yet known how much.
'Enthusiastic and mature'
Pc Beshenivsky had been a police community support officer for two years before becoming a police constable in February 2005.
She had three children and two step-children, lived in a converted barn in Keighley, West Yorkshire, and was killed on her youngest daughter's fourth birthday.
West Yorkshire's Chief Constable Colin Cramphorn said Pc Beshenivsky joined her Bradford patrol team in May after completing her training and was described as "an enthusiastic, mature and very positive colleague".
He added that Pc Milburn, who comes from a large family in the Bradford area, had previously been a machinist and was hoping for a "complete change" and "new opportunities" in joining the force.
The shootings have raised calls for police to be better equipped or even routinely armed.
Pc Beshenivsky had been wearing body armour which gave limited ballistics protection.
However, Tom McGhie, chairman of the West Yorkshire Police Federation, said: "There are types of body armour which offer a much higher level of ballistic protection but the problem is they would be almost unwearable."
And Home Office minister Hazel Blears rejected calls for the police to be routinely armed.
"It is important that the police have a very close relationship with the public and for them to routinely carry guns might put that relationship at risk," she said.