Ms Dando, who had been due to commentate for the BBC's television coverage of the marriage of Prince Edward and Sophie Rhys-Jones, was gunned down outside her home in Fulham, London, on 26 April.

Her fiancé, consultant gynaecologist Alan Farthing, has described his ordeal after learning that she had been killed, in an interview with the Daily Mail newspaper on Saturday.

And he has reissued his appeal for people to come forward with any information which could help catch the person or people responsible for her murder.

"The person who killed Jill was a brutal, callous, calculated murderer who has taken one life and destroyed many others.

Many floral tributes were laid outside Ms Dando's home

"Not knowing why she's been killed adds to the difficulties. I am forever wondering why. My main priority is to do everything I possibly can to help the police catch Jill's killer or killers."

In the interview, Mr Farthing describes how police drove him from his work at St Mary's Hospital, London, to Charing Cross Hospital where Ms Dando, 37, had been taken after the shooting.

'I wanted to stay with her'

He said: "They took me down what seemed like the longest corridor in the world to the casualty department and to a side room where Jill was lying.

"She had a towel wrapped around her head as if she had just got out of the bath, though it was not covering all her hair. I could see it was Jill's hair. She had a wound in the back of her head that wasn't obviously visible to me.

"She was lying in a hospital gown looking peaceful and she was still warm. I held her hand, which was still warm, and confirmed to the officer that it was Jill.

Alan Farthing arriving at Ms Dando's funeral

"I was then asked where I wanted to go, which was a decision that I was incapable of making at the time. I wanted to stay with her and carry on holding her hand."

Mr Farthing, who had been due to marry Ms Dando in September, describes how he was in a state of complete shock after hearing of the shooting.

He said: "I went to stay at a friend's that night. When I left the police, I was walking down the road to my friend's car. We passed two street sweepers, one of whom I heard saying 'You know that woman from Crimewatch, it was her that's been killed.'

Focus on four areas

"It was a surreal experience - particularly then seeing the Evening Standard billboard headlines saying that your fiancée's been murdered."

Detective Chief Inspector Hamish Campbell, in charge of the day-to-day running of the murder inquiry, has asked people to help them as they focus on four key areas.

Police want to trace the driver of drivers or a blue Range Rover seen three times in and near Gowan Avenue where Ms Dando lived, in the hour before she was shot.

They also want to trace the 9mm weapon used in the attack, which they say was a rare, short version of the weapon.