No one from the police showed up in Cutting Edge: Did Barry George Murder Jill Dando? The shooting of Dando has probably excited more media attention in this country than any other single crime in recent history - which means in history. We feel we know everything there is to know about the murder. And we're right, because there's so little that is known.

All of the tiny knowledge that exists was neatly assembled by Cutting Edge and placed next to the troubled figure of George, an epileptic fantasist with a low IQ and past convictions for indecent assault and attempted rape. They did not match up well. The forensic evidence was bordering on negligible, and it was also contaminated in police custody. The rest of the police case was built on the fact that George, the fantasist, lied to them; he was identified by a small minority of witnesses as being near the scene of the crime (he lived not far away); and he had an obsession with celebrities (as do most Heat readers), although not, apparently, with Dando.

The tone of the documentary was scrupulous, never allowing itself to become distracted by cheap attacks on the police enquiry. Its aim was simply to question the evidence. The one certainty it established was that in this case there was nothing approaching certainty. Dando's death is a mystery that is only slightly more baffling than the mystery of how a jury found George responsible for it.

A more disturbing side to obsessive behaviour was documented in Did Barry George Kill Jill Dando? (C4, Mon). Was George just a confused loner in the wrong place with the right magazine clippings in his bedroom at the wrong time? It seemed so, from the evidence provided here by neighbours and psychiatrists.

This investigation was gripping stuff, and a far better exposure of the seedy underbelly of everyday TV life than When Steptoe Met Son (C4, Tues), a disappointing secret history of the sitcom's stars that might have seemed more revealing if a) it was 1962, and b) the thought of an ageing celebrity going to Hong Kong to have sex with teenage boys seemed at all out of the ordinary.

If you were going to finger someone for a celebrity murder in which little progress had been made in a year and the public pressure for a result was unbearable, Barry George would be just the man. A mentally retarded fantasist with an interest in guns, he had a previous conviction for attempted rape and rolls of undeveloped photographs of women walking the street littered his house. He lived half a mile from Jill Dando. Did Barry George Kill Jill Dando? claimed that all that was needed was more evidence.

Although a British court recently upheld George's conviction, ruling that the evidence against him was compelling, the programme suggested the evidence was stretched very thinly indeed over the case.

The documentary highlighted perceived inconsistencies in the case, particularly the following. Questionable forensic analysis was accepted by the court. The professional nature of the killing did not indicate a suspect with severe epilepsy and an intellectual ability that placed him in Britain's lowest 1 per cent. The central witness testimony came from a woman who had seen the suspect for six seconds, 18 months before being asked to identify him. If you were to collate the reports of the 16 witnesses, the killer could be described as an olive- or white-skinned man, with black short or long wavy or curly hair. He is between 5 feet 8 inches and 6 feet in height and on the day of the killing was wearing a coat or suit, and was sporting a Trilby hat. Or not.

It was a documentary that lacked balance, but then balance has hardly been a motif of the case. The alternative theory - that Dando was killed by a Serbian assassin - does not play too well on the front page of the Sun. George is not a man the media is interested in standing up for. The replay of Trevor McDonald on the night he read the news of George's conviction for Dando's murder was instructive. He appeared to editorialise with every inflection. When he described George, this 40-year-old gun-fanatic loner obsessed with female celebrities, he seemed to do so with the disgust of a man taking a bite of raw meat.

EVERYONE feels a little queasy at the idea of another miscarriage of justice to add to the melancholy list of 'unsafe' convictions that have had to be righted in recent years.

Last night's Cutting Edge did its best to argue - relying on experts who were not concerned in the actual trial, and friends and relatives of the accused - that it could happen again in the case of Barry George, sentenced to life for the murder of TV presenter Jill Dando.

Only last month, the Court of Appeal upheld the outcome of the trial as 'compelling', while acknowledging that it had been a complex and difficult case.

This programme explored what it saw as weaknesses and inconsistencies in the prosecution's charge that George, a loner interested in guns and obsessed with celebrities, had indeed killed Ms Dando.

Other questions that could be asked, but were unexplored in this Cutting Edge, concern modern police detection methods.

There must be worries over the intensely bureaucratic approach now adopted in all high-profile murder cases, where the police assemble large numbers of desk-bound detectives to sift information, before returning (as in the George case) to evidence they already had in the earliest days of their investigation.

Whatever happened to oldfashioned detection - or does it only happen in TV cop dramas?

As rhetorically as Who Killed Simone Valentine?, Cutting Edge (Channel 4) asked Did Barry George Kill Jill Dando? Unlike Trail of Guilt, this Cutting Edge undermined one's faith in the police, effectively demolishing any notion that George's conviction for the murder of Dando is safe, that his guilt is beyond a reasonable doubt. Hardly "Don't have nightmares, do sleep well" television, it was, nevertheless a legitimate examination of Dando's murder. Sometimes, certainty is a luxury.

The Appeal Court recently decided that the question Did Barry George Kill Jill Dando? could safely be filed alongside those proverbial queries about the toilet habits of bears and the religious affiliations of Popes. It is, in other words, a question expecting the answer "yes". For Channel 4, though, this was an interrogation of a more straightforward kind. In contrast to the BBC's Trail of Guilt - an unabashed celebration of the triumphs of modern police work - their documentary about the George conviction set out to make us re-examine that most dangerous of all verdicts - "He must have done it".

Barry George did make a very juicy suspect. He'd followed women around, had pictures of television presenters in his flat and had posed with a handgun - the photographic evidence of a long fascination with the SAS and the army. For a police force under pressure after a year of fruitless investigation, he must have looked as if he had a big red bow tied round him, particularly after a witness had placed him in the vicinity on the day of the crime. When forensic scientists discovered a tiny particle of firing residue in his pocket, it looked as if they had their man. George (left) obligingly behaved suspiciously when questioned - the only problem being that he behaved suspiciously even when he was buying a pint of milk or chewing gum - two activities which, according to those who knew him, he would have had some difficulty combining. "He's the sort of bloke, you throw him a tennis ball and he'll miss it," said one acquaintance, mocking the notion that he might have effectively carried out a daylight hit. This is a prejudiced judgement of course - but an adversarial judicial system depends on prejudice for its operation, some opposed and some in favour - and there wasn't a lot of the latter about when George was on trial for murder.

There were other worrying features about the evidence. The coat in which the incriminating single particle had been found had been unpacked and photographed before it was sent to the forensic labs, an elementary breach of basic practice. There was considerable confusion among the eyewitness accounts of the man seen at the time of the shooting, with several insisting that the suspect had shoulder -length hair, including one of the Crown's most important witnesses. George had always had short, cropped hair. Even the apparently sinister fact that he had collected pictures of Jill Dando looked more innocuous after you'd heard the details - out of 800 newspapers found in his flat, only eight contained pictures of Dando from before the murder. Given her ubiquity in the tabloids, it was something of an achievement to have so few.

It isn't impossible that he did it, even so. The incredulity of your neighbours is hardly a solid alibi, and people have murdered before and left less evidence behind. Shortly before her death, the Radio Times published a provocative cover photograph of Dando that could easily have swung her into the crosshairs of a psychotic looking for a target. What you really couldn't say any longer, however, was "beyond reasonable doubt".

The chief suspect for a series of rapes and murders in Rochdale also "looked a wrong 'un", according to the local newspaper editor. But in this case, covered in BBC1's Trail of Guilt, the police had more than intuition to go on. They had DNA evidence, bloody handprints, clothing fibres, shoe impressions, splashes of the victim's blood in the killer's home - everything, in fact, short of a video showing him committing the crime. Compared to this Matterhorn of incrimination, the evidence against Barry George couldn't even be described as a molehill