Education: Playing the detectives: In Derbyshire, pupils are taking the law into their own hands - with the full approval of the police. Julia Hagedorn investigates

'LAST NIGHT Celia Green was murdered as she made her way home from the surgery where she worked. The investigating officers have taken statements and you will find them, along with the forensic evidence from the scene of the crime, over there on the tables.

'This is now the murder investigation room and you are not entitled to discuss this case outside the room or you will jeopardise the investigation. Now get on with it.'

The team of detectives were not dressed in plain clothes, but regulation turquoise T-shirts marked Granville Community School. This murder investigation was being carried out by 14-year-olds taking part in an exercise devised by PC Chris Hartshorn as part of a Derbyshire Police community liaison programme that 'develops links with schools in a non- confrontational way'.

Roger Worrall, a colleague who helped write the murder investigation materials, put it more graphically: 'We are not seen any more as 'grunts' and 'pigs'.'

PC Hartshorn, along with two other policewomen, covers all the secondary schools in the city of Derby, as well as several in the outlying area. Schools are the biggest captive audience the police can have, she explained. She estimated that her team was now known to 6,500 pupils.

In the investigation room, pupils formed into groups of six, chose a senior investigating officer, two detectives, two officers from the scene of the crime and a note-taker. PC Hartshorn had given them a terse brief: no single person can solve the crime, this must be a joint exercise, they must set up an information-recording system, and they must choose a leader whom they respect.

The pupils moved over to a video reconstruction of the crime, including a dramatised version of Celia's last actions before she was murdered. Her scream as she is knifed pierced the room at regular intervals as pupils returned again and again to the video in the hope that it would yield further clues.

At the tables, animated arguments were taking place over the murderer's identity - sometimes backed up by a little real detective work, matching hair and fibre samples from suspects with those found at the scene of the crime, checking on the fingerprints on the knife, or trying to trace the owner of a shoe left beside the body. Two or three pupils were painstakingly working through written statements.

'A torn bit of letter was found by the body, showing she was having an affair. The matches say she is meeting someone in the park at five o'clock,' puzzled Gareth Brewin. 'Here's a parking ticket, too, which might have come from the car park by the leisure centre. The pen has the name of Steve's Disco on it and she might have got it from Steven Browner - see if the ink in the pen found by the body matches it.'

Steven Browner was also the prime suspect at the next table, but this was being hotly contested by Verity Shaw, who was convinced the killer was Dr Goode, Celia's employer.

'It says the splashes of blood on his jacket were from a patient, but he would be wearing a white coat when he saw the patient, wouldn't he?' she insisted.

Time was running out and each group had to appoint someone to put forward an argument for their prime suspect. It was a near thing, but Verity lost out. 'OK. You're the leader, Prentice. If you're so sure then you do it. I haven't got the guts.'

As PC Hartshorn pointed out, a valuable part of the exercise was to get the pupils to take orders from each other and decide their own agendas - something usually done by their teachers.

When it came to the evidence, each group had a different suspect, and none was convincing enough to convict. Daniel Borton had linked fabric from Browner's coat to fabric at the scene of the crime, and put forward a good argument for his motives in killing Celia: she was about to tell his wife about the affair. But Daniel failed to match the fingerprints. Andrew Booth had found the doctor's fingerprints on the knife but could not think of how he had come by it. Jane Robertson thought it was Samuel Dent because he had admitted to rape 20 years before and she had matched fingerprints, hair and coat fibre. However, Jane could not explain how, if Celia had not known him, she had appeared in the video to recognise her murderer.

In the end, somewhat to the pupils' disappointment, PC Hartshorn told them that it did not really matter who the killer was: the point was that they had to prove their suspicions beyond reasonable doubt. 'You have worked well as teams,' she told them. 'Some of you have fallen out, which is how life is. You have learnt that you don't solve a murder in isolation, but I can't tell you who the murderer is because you haven't convinced me yet.'

Of course, if the murder had a clear solution, the exercise would have a short shelf-life as word went round adjoining classes and schools.

So what had the pupils got from it? Some loved it, others found it stressful. There was much raucous laughter from the boys: 'We haven't learnt anything. We were doing it to get out of lessons.' The girls were more serious. 'Everyone picks on the police and says they don't do anything, but when you have done this, you know how hard it is,' said Rachel Staley.

For PC Hartshorn, the exercise is about building up 'good quality relationships and letting young people see the reality, as opposed to the image - we are not big, bad ogres'. Next year when she comes to see the same pupils in the next instalment of her programme, they will remember her as a person, not a stereotype.

Schools have been so enthusiastic about the murder investigation exercise that 50 sets of material, presented in a smart briefcase, have been produced with the help of funding from Derby Safer Cities Project and distributed round the city. Last month, PC Hartshorn travelled to London to show the pack to the Home Office. She hopes the investigation will spread wider than Derby.

(Photograph omitted)