'I think he killed her - but even now I can't be sure'

When people hear that I have written the biography of Jill Dando they almost always ask, straight off, not about her but about Barry George. Did he kill her, then? Do you think he did it? Did he

It seems the doubts about the guilt of the man convicted of her murder are, sadly, more interesting than the detail of her life. Those doubts will not be quelled by yesterday's Appeal Court ruling upholding his conviction and nor will they have been allayed by the hearing that preceded the judgment.

Even those who believe in the certainty of his guilt, such as Hamish Campbell, the senior police officer who led the murder inquiry, still struggle to explain it, give it reason and, more significantly, motive.

Motive is a key ingredient in any conviction - "motive, means, opportunity" is the mantra of any murder squad - yet who can say why Barry George killed Jill Dando?

"Not for nothing" was the somewhat inelegant phrase which her family and closest friends and colleagues deployed in support of the charity they set up after her death, the Jill Dando Fund. There was no suspect then, in those early days - it took the police a year to get to George - and none of the people who knew her, much less the police, could understand why she might have died.

SHE was not quite the saint of popular imagination - she double-dated sometimes (shock) and lost her temper occasionally (horror) and was really rather ambitious (no, I don't believe it) - but not being a saint did not justify being killed by a single bullet from a gun pressed tight to her head by a gunman standing intimately close.

In such a terrible void, her friends and family sought to give her death meaning and purpose through the charity. Jill had been keen on charity herself, perhaps seeking to give her life some meaning and purpose, too. The idea that she had not died in vain was important, something to cling to in the midst of grief. Her friends and family, I know, kept faith with Hamish Campbell and always believed the murderer would be caught in the end, just as Campbell said he would. They naturally assumed that with an arrest would come an explanation.

Instead, they got Barry George and with him the painful realisation that, actually, Jill Dando's death had no meaning at all, was merely, apparently, the aberrant act of a disordered individual. Alan Farthing, who would have married Jill Dando had she lived, believed in George's guilt, but not knowing "why" still nagged away inside him and made it hard to be 100 per cent sure.

Hamish Campbell spoke to me of the internal jealousy he felt within the Met, the silence of some fellow senior officers when the verdict came through, which contrasted with the congratulations of others. Campbell sensed people's disappointment that such a dramatic death should come to such a banal conclusion. What, him? Is that all? What about the Mafia, a lover, Kosovo?

In the vacuum of reliable information about her death there had been many outlandish theories, often floated in the Sunday tabloids: the Russian mafia godfather whose advances she had spurned while on a TV Holiday assignment; the gamewarden boyfriend from South Africa who knew about guns; the Serbian warlord who had dispatched a death squad to London to assassinate Jill because of her participation in a televised appeal for Kosovan refugees.

There never was any credible evidence for any of this, though that did not prevent defence barrister Michael Mansfield from invoking the Kosovo theory as an alternative to his client during the Old Bailey trial last summer.

The defence team's trawl of the police investigation files turned up a spurious intelligence report that Arkan, a Serbian military leader, had ordered Jill's death. When the full text of the report was later read out in court it revealed that the source of the claim also said Jill was killed because she had incriminating information about a north London crime family. Ah. Right then.

It was not, of course, the job of the defence at the trial to demonstrate who had killed Jill Dando, any more than it was their responsibility to prove that Barry George was innocent.

The burden of proof was solely with the prosecution. It was up to them to persuade the jury that George was guilty beyond reasonable doubt.

Still, it seemed significant that Mansfield had no real answer to the prosecution case, could offer nothing to suggest George's innocence. Nor did a year's passage seem to have made any difference. No one had turned up anything new for the appeal. Not Mansfield, nor any campaigning, investigating journalist, nor any miscarriageof-justice group nor anyone else who might have had information to offer.

All that was new were two separate tape recordings which had allegedly caught George making prison confessions. Neither the defence nor the prosecution gave these tapes any credence.

For myself, I was increasingly persuaded that Barry George had killed Jill. I believed that was him in the street that morning and him running from the house following the shooting and him walking in the area soon afterwards. They were three distinct groups of sightings, each in different clothing, but he lived so close by that it would have been easy for him to go home and change.

I did not think he had planned the murder very carefully, if at all. There was no evidence that he had stalked Jill Dando; no evidence he was ever really very interested in her at all. The fact that he lived in total domestic chaos made it inconceivable that he had destroyed such evidence.

BUT, roaming the local streets as he did, he could not have missed her and what a prize she must have presented to a man who habitually followed local women, who had 2,597 undeveloped photographs of 419 women scattered around his flat in dozens of loose rolls of film.

Perhaps he approached her and she gave him the brushoff. Maybe that was all it took. Right, he thought. And went home and got his coat with the gun in the pocket. He was, I suspect, capable of great anger and there was great anger, rage, in the hard contact of the gun pressed against Jill Dando's head.

Maybe that's what happened. Maybe it didn't. I think he killed her, but I can't be sure. And not being sure, I couldn't have convicted him. All About Jill: The Life and Death of Jill Dando by David James Smith (Time Warner Books, £7.99).