It was just after 6am on March 22, 2005; 45 minutes later Simon Murden was dead, shot six times by police marksmen after driving the wrong way up the eastbound carriageway of the A63.

He had crashed into another vehicle and was walking along the road carrying three African swords.

In a painful admission at the opening of the inquest into the 26-year-old charity worker's death, David Murden wept as he said he felt partly responsible for his son's death because of the calls he had made.

Yet the family remains convinced the tragedy was avoidable.

Mr Murden told the Yorkshire Post: "When you ring the police you are giving them a duty of care. I was saying Simon wasn't well and he'd left the house in a terrible state and I didn't think he was fit to drive a van."

Officer C, who with firearms colleague, Officer D, carried out the shooting, told the inquest he knew Mr Murden was a member of the "special population group", which can include people suffering temporary or permanent mental illness.

The Murdens believe this should have had more bearing on police handling of the incident. They also say the two officers failed to use a simple tactic which may have defused the situation. Simon's mother Dorothy said: "They didn't use his name, if they'd said his name it might have helped to bring him down. He clearly wasn't there. The police officers were not trained in any way to deal with someone who was a member of this population group."

Mrs Murden said she also believed the officers had acted in haste – Mr Murden was fatally wounded within 45 seconds of the officers arriving at the scene.

The family's anguish was not helped by their contact with police after the shooting.

An officer who was part of the team which visited the Murden household that morning had a comedy ringtone on his mobile phone, which Mr Murden eventually asked to be switched off.

And the car which was sent to collect them could not cope with the country lane leading to their Beverley home once it was full – leaving Mr Murden to get out and walk.

The family were also horrified to find officers sealing off and searching Mr Murden's bedroom.

They say they find it bizarre that successive chief constables have tried – and failed – to assign them a police family liaison officer.

The Murdens have found that when the state kills it does so anonymously and with little explanation. They have also discovered the state machinery to be almost as unforgiving as the bullets which took Simon Murden's life – Mrs Murden is still being pursued for thousands of pounds to cover her legal costs at the inquest.

She said: "We are just little people in the midst of the powers that be. We are swimming against it all the time and yet we are the victims of this horrendous event."

It has taken them three years to hear the officers who shot their son explain their actions in the formality of a coroner's court. And yet still questions remain.

The shooting was initially investigated by the Independent Police Complaints Commission, which prepared a file for the Crown Prosecution Service.

Sheelagh Judge, then of the CPS specialist crime centre in York, and her advisers Robert Smith QC and Adrian Waterman QC, all agreed there was sufficient evidence to charge both officers.

The principal offence they considered was murder, and they also considered gross negligence and manslaughter.

It is not known which offence they felt may have been committed.

The Director of Public Prosecutions, Sir Ken Macdonald, took a different view.

Although Ms Judge and her counsel maintained their position, Sir Ken said he had "reservations about the sufficiency of the evidence" and decided not to prosecute.

The family was denied leave to appeal against the decision.

The Murden incident remains the only time in its history that Humberside Police has used lethal force.