Television Review: Odd mixtures of the forensic and the fictional

It's not been a good week for the police on television. On Monday World in Action (ITV) revealed (if revelation is the appropriate word) that some police officers like to unwind with a Ku Klux Klan Nite down at the local dog-track. Now, on two successive evenings, David Jessel has been demonstrating that they're not always much more engaging when they're on duty. Trial and Error (C4) presents itself as a case for the defence - another chance for the legal lottery's losers - but it's always a sly arraignment too; an implicit charge of sloppiness, expediency, perhaps something even worse, on the part of the policemen originally involved.

The films themselves are an odd mixture of the forensic and the fictional; as Jessel tells his story the camera prowls like a killer through the darkened house and the narrative is perfectly paced to leave the big revelations just before the commercial break. These are detective dramas, slow strip- teases which work on our lust for resolution. First the question marks, oddities which the court chose to ignore, then the answers, unveiled with expert, tantalising delay.

That said, the detective work is extraordinarily assiduous. A good prosecution lawyer would make short work of around a quarter of what you see - as hearsay or speculation - but even the best lawyer would pass over the rest in embarrassed silence, praying that the jury wasn't paying attention. In Wednesday night's case, for example, that of a labourer convicted of the murder of an 84-year-old woman, Jessel used the mute testimony of an electricity meter to cast serious doubt on the official time of death, exhumed some important evidence the police had ignored and threw a decidedly unflattering light on the chain of connections that linked Bryan Parsons to the murder weapon.

At the building site where Parsons worked the police discovered a coat. Its pockets contained fibres identical to those on gloves found next to the murder weapon. But to link the coat to Parsons, the police depended on a scrap of yellow paper also found in the pocket. On it was written the telephone number of a police station, given to Parsons when he had volunteered some information about the murder. But when Jessel showed this evidence to the receptionist involved she revealed that it was the wrong type of paper. It turned out to come from another woman, a policeman's wife, who also remembered Parsons volunteering information, at the same time but at a police station two miles away. Jessel allowed himself a sardonic flourish of style: "Two visits? Two police stations? Two pieces of yellow paper?... Too good to be true?"

Last night's story, that of a 17-year old convicted of the brutal murder of an insurance salesman, was a little less convincing in the case it mounted, though it delivered at least one memorable coup. A claw hammer, like that used to remove the victim's face, had gone missing at the hostel where Jason Warr lived, a fact the police took as damning corroboration. Jessel and his researchers doggedly tracked the missing hammer, through groundsmen's receipts and dentally-challenged burglars, until they discovered it, still in the possession of the man who had reported its "disappearance". His shifty recantation was as damning as anything else - powerful evidence of the self-serving malleability of the police's hostile witnesses. The programme also included the year's best Freudian slip, delivered by the victim's widow. After Warr's conviction, she had been charged (and acquitted ) with inciting her son to commit the murder and she benefited considerably from her husband's death. How much money did you inherit, asked Jessel. "I'm not quite sure, I can't be honest," she replied. You drew your own conclusions from the fact that they hadn't asked for a retake.