Day by day in south London, at a public inquiry before a former High Court judge, the details of Britain's most notorious race killing and its equally notorious aftermath are being sifted and scrutinised. The conduct of the police has been severely criticised; the justice system will be, too. Five white youths who were charged but never convicted of the crime are to be heard. Stephen Lawrence's parents stoically bear witness.

Their son was attacked and left to die in Eltham on 22 April 1993, by people he had never seen or spoken to. He was, according to the tired old expression, in the wrong place at the wrong time. But how did he come to be there? And how did he come to die? The following is an attempt to reconstruct Stephen's last day, drawing largely from evidence given at the inquiry.

It was a schoolday. Stephen was 18 and due to take his A-levels that summer; his studies were split between Blackheath Bluecoat School, which he had attended since he was 11, and Woolwich College. On Thursdays, he went to school. He stayed in bed that morning while his younger brother and sister dressed, so they had breakfast and set off ahead of him.

Doreen Lawrence, his mother, was away; she was on a field trip as part of a university degree course she was doing now the children were growing up. Stephen's father, Neville, was at home; they had a cup of tea together. Neville, who had been out of work for some time, was feeling low, and went back upstairs after they had chatted. Stephen put on his anorak, fetched a bag of school things and went to say goodbye. Neville's thoughts turned to the evening: "Don't go anywhere, because your Mum's coming home later," he said.

"Are you OK?" Stephen asked.

"Yes," came the reply.

"Are you sure you're all right, Dad?" Yes, again. Neville watched from the window as his oldest child, now a young man hoping to go to university and train as an architect, walked off down the road.

Stephen Lawrence at 18 was 5ft 8in tall, slim, fit - since his days as a Boy Scout he had loved athletics and won various prizes and certificates. He was good-looking, although still, perhaps, with a trace of adolescent gawkiness. He wore his hair fashionably short with a pattern razored into the sides. His clothes were the uniform of his age: cords and trainers, layers of sports-labelled T-shirts and sweatshirts, an anorak. In character, he was good-humoured, unassuming and sensible. He knew how to have fun but was never loud, and his friends valued him for his calmness and thoughtfulness. His teachers liked him. He was, in short, good to have around.

That Thursday, he emerged from a morning of classes at 12.40pm to meet his friend Duwayne Brooks outside the school gates. They had known each other since they were 11, and had been good friends for the past four years or so. Thursday was Duwayne's day off from Lewisham College and they had made a vague agreement to meet some girls from the John Roan School, on the edge of Greenwich Park. The rendezvous was a chip shop five minutes' walk away, so they strolled down. When they got there, they played a couple of video games before deciding to wander on in the direction of John Roan school, to see if there was any sign of the girls. At about 1pm, they gave up and headed back to Stephen's school, chatting at the gates for a few minutes, arranging to meet again after school.

At 3.10pm, they caught the bus to Lewisham, where they hung around the shopping centre for a while until they spotted Anne, a friend of Duwayne's whom he had not seen for some time. Anne lived in Grove Park and the three of them decided to head off there together, catching another bus. It was now about 5.45pm.

Stephen's plan was to go to the house of his uncle Martin, who lived close to Grove Park. Duwayne, however, wanted to see Anne home first, so they split up, Stephen going directly to Martin's and Duwayne accompanying Anne part of the way to her home before jumping on another bus and rejoining his friend at his uncle's at about 6.30pm. For the next three-and-a-half hours, Stephen and Duwayne chatted and played Nintendo games - a recent passion - and ate dinner with Martin.

Stephen had probably forgotten that his father had asked him to be home early, but he knew that his regular curfew hour was 10.30pm, so just before 10pm he and Duwayne set out for home. The journey before them was not long, about three miles, but required some bus-hopping. Unless they had unusually bad luck with connections, Stephen would be back in Plumstead soon after 10.30pm.

They walked to a stop in Dunkery Road and caught a number 126 bus to Eltham High Street, getting there at around 10.15pm. They went around the corner into Well Hall Road and waited for a number 161 that would have taken them to Woolwich. After a couple of minutes, they became impatient and decided to walk down to Well Hall Roundabout, where there was more choice of buses. If anything came along as they walked, they could run for it. Sure enough, they had not gone far before a 286 overtook them. They chased it to the next stop, opposite Eltham railway station, where, fortunately, it was delayed, and they caught up and boarded. The delay was caused by a young French au pair, Alexandra Marie, who was asking the driver how to get to Shooters Hill. The 286 wasn't going all the way there, but the driver told her to get on.

Duwayne suggested to Stephen that they stay on the 286 all the way to Blackheath Standard, then change to a number 53, which would take Duwayne to his home in Charlton and Stephen on to Woolwich. Stephen favoured a route that was more direct, for him at least. This meant getting off in a couple of stops, at the Coronet cinema close to Well Hall Roundabout, then crossing over and taking a 161 or a 122 over the hill to Woolwich. Duwayne agreed to this; he wasn't the one in a hurry.

So they got off at the cinema, as did an older, white man, Royston Westbrook. The bus stopped again at the edge of the roundabout, where Alexandra Marie got off. There was no stop there; the driver was bending the rules a little to help her. He told her to cross the roundabout to a bus stop on the far side and to wait there for a 122. A 161 would do just as well, he added, but there was talk of a strike and there might be no more that night.

The boys and Westbrook were heading the same way as Alexandra Marie, so they walked behind her across the middle of the roundabout to the bus stop about 50 yards further up Well Hall Road, just past the junction with Dickson Road. Alexandra Marie got there first and looked at the timetable; one of the boys arrived, looked over her shoulder and declared: "A couple of minutes." It was 10.25pm.

Alexandra Marie sat on the ground with her back to the bus shelter while Duwayne and Stephen chatted nearby. To the French girl, they seemed happy, and she thought she saw one of them practising a few dance steps. Royston Westbrook heard the boys talking about football. He saw the same foot movements but interpreted them differently; he thought one of them was kicking an imaginary ball.

Two minutes passed, then three, then four, then five, but no bus came. A fifth person joined them at the bus stop, a blond 18-year-old called Joseph Shepherd, who also walked up from the direction of the roundabout. Joey, as he was known, lived on the same estate as Stephen and the two knew each other by sight, but they were not friends and did not acknowledge each other.

Stephen and Duwayne became restless. It was after 10.35pm now; they had waited more than 10 minutes. Stephen was late and beginning to contemplate the ticking-off that awaited him. Duwayne began to think again of his suggested dog-leg route, which would mean going round the corner to catch the 286 in Rochester Way, but Stephen was reluctant. Stephen was almost home; it was just a mile and a half over the hill. If a bus came along, he could be there in a few minutes. He agreed, however, to walk back towards the roundabout, to a point from which they would be able to see across and down Well Hall Road; that way they would know if another 286 was on its way in time to get around the corner into Rochester Way.

It was just 50 yards to the roundabout, but their progress towards it betrayed their differing inclinations. While Stephen hung back, Duwayne moved ahead, crossing Dickson Road. As he did so, he noticed a group of youths - white youths - over to his left, crossing Rochester Way where it left the roundabout on the eastern side. He thought he had glimpsed these boys a little earlier, when he got off the bus by the cinema. Now he wondered fleetingly what they were doing. At the same moment, however, Duwayne spotted a 286 coming up the lower part of Well Hall Road. "Can you see the bus?" he asked Stephen, who was 10 yards behind. There was no reply. Duwayne now looked again for the bus, to see if it had reached the cinema stop where he and Stephen had got off earlier. As he looked he realised that the group of white youths - there seemed to be six of them - had come much closer and were on the other side of Well Hall Road.

Duwayne was now aware of danger, but Stephen was concentrating on the bus, checking that it really was a 286 and trying to decide whether they should dash around the corner to catch it, or wait for a direct bus. Absorbed, he had drawn closer to Duwayne and moved past him, so he was now standing in the middle of Dickson Road. "Can you see it?" asked Duwayne urgently. He did not hear Stephen reply. Instead, from across the road, he heard the shouted words: "What? What? Nigger!" Whipping around, he saw the white boys charging across the road towards them.

The one in front - Duwayne thought that this was the boy who had shouted - was staring at him. "Run! Run!" he shouted to Stephen, and took a few paces back up the hill, in the direction of the bus stop. He looked back and saw that Stephen had not moved. The white boys were upon him. Duwayne saw the leading boy draw something long from inside his clothing. He saw this object again as the boy raised his arm above his head and brought it down on Stephen. Then, while others in the group surrounded Stephen, one white boy who had momentarily been hidden by a tree suddenly appeared and chased Duwayne. Duwayne retreated and his pursuer gave up and went back to join the attack on Stephen, who was on the ground. Then the white boys ran off down Dickson Road.

It had been so sudden that even Stephen himself did not realise the seriousness of what had happened. He knew he had been hit, and hit very hard, but fear and adrenaline drove him on. Getting to his feet, he began to run across Well Hall Road, in the opposite direction from his attackers. Soon, however, he realised that his right arm was not working - it hung numb and limp at his side - and he felt the wetness of blood on his front. "Duwayne!" he called out in alarm, but his friend insisted, "Just run!"

Stephen managed to cover more than 200 yards up the hill behind Duwayne, but his body was not working properly, he was slowing down and progressively losing feeling. His head was reeling. He called out, "Duwayne, look at me, tell me what's wrong." His clothes were dark and it was night, but looking closely now, Duwayne could see by the orange light of the streetlamps that his friend was soaked with blood, and that it was gushing out through his clothing just below the neck. Duwayne was appalled, but he was also still afraid that the white boys would come back for more. "Just keep running," he said, breathless. "I can't," protested Stephen, putting his hand to his chest. "I can't." And he slumped to the ground.

Duwayne was terrified and in shock and now he realised his friend might die. But he did not quite panic; he looked for help. Directly across the road, he saw a public telephone. He ran over and dialled 999. He was very scared; Stephen was alone by the roadside and the boys might come back. Putting the receiver down on the shelf for a moment, he stepped back to look down the road. He saw a couple on foot and called out or gestured to them for help, but they seemed just to hurry on, which made Duwayne more frantic.

He went back and picked up the phone again. Shouting, he asked for an ambulance and said that his friend had been hit on the head with an iron bar. The operator asked who he was and he gave his name. She then asked where he was calling from. He hesitated. The question came again. Where was he? The operator told Duwayne to look at the address given above the phone. Duwayne read a postal code. The operator asked for more but Duwayne, speechless with frustration and shock, dropped the receiver, kicked the telephone stand and turned away.

He knew that the Brook Hospital, with its accident and emergency department, was less than a mile away. By car it would take three or four minutes. Would that not be better than waiting for an ambulance? He ran into the road to flag down a passing car, but there were not many drivers on the road - it was now 10.45pm - and those that were, did not want to stop. One slowed to a halt, raising Duwayne's hopes, but suddenly accelerated off past him. Rage and despair flood the young man's mind. First the couple on foot, now this. Why would no one help? What could he do to save Stephen? Should he be doing something to stop the bleeding? Then at last a light- coloured car pulled up and a couple got out and crossed over.

When they reached Stephen they found another couple already there. Conor and Louise Taaffe, local people who had been on their way home from a prayer meeting at the Catholic church on the other side of the road. It had been the Taaffes whom Duwayne had seen before he made his 999 call, and whom he had thought had walked away. In fact, they had seen Stephen fall and sensed something was seriously wrong, but initially thought it might be a mugger's trap.

The driver who stopped to help Duwayne was an off-duty police officer, James Geddis. His wife, Angela, who was with him, knelt beside Stephen as Duwayne asked urgently: "Is he still breathing?" She said he was. PC Geddis asked if an ambulance was coming. Duwayne, distressed, pointed to the telephone and said he had tried but did not know if the message had got through. Geddis crossed the road, picked up the hanging receiver and spoke to the operator. He returned to say help was on its way, then fetched a blanket from his car and put it over Stephen. Duwayne kept asking, "Is he still breathing? Is he still breathing?" Stephen's breath was now faint and shallow. They thought he seemed peaceful and not in pain. Mrs Taaffe, feeling there was nothing else she could do, prayed.

Duwayne was pacing up and down, wondering where the ambulance was. He was angry at the whole situation, angry at his own powerlessness, angry that the people who had turned up seemed to make no difference. He recognised the Taaffes as the people he thought had ignored him a few moments earlier; that made him more angry. Then he heard a siren and saw a flashing light on the road. His hopes rose, but it turned out to be a police car. His feelings boiled over. "Where's the fucking ambulance? I didn't call the police!" he screamed as two officers stepped out. The time was now 10.50pm; about 10 minutes had passed since the attack.

Duwayne was angry with himself, too. He was afraid that because of his own panic the first 999 call had not really got through and valuable time had been lost. He was wrong. The British Telecom operator received his call at 10.43pm and, despite the difficulties of the conversation, she was able quickly to trace it to the public phone. She alerted the London Ambulance Service, advising them that a hysterical male had reported that another man had been assaulted with an iron bar and was injured at the scene. An ambulance was despatched from Greenwich Hospital. The operator passed the same message to Metropolitan Police Headquarters at Scotland Yard. Their radio alert had brought the police car.

In that car were WPC Linda Bethel and PC Anthony Gleason. As he got out, Gleason radioed for back-up, then he made straight for Stephen, checked his pulse and found it very faint. Without moving Stephen, he checked his head for signs of the reported head wound. Finding none, and still without moving the body, he made a quick visual check to see if there was any sign of a wound elsewhere. He could see nothing; Stephen was lying mainly on his front.

Meanwhile, Bethel radioed in to check that the ambulance was on its way, and was told it would be three to four minutes. She tried to calm Duwayne and to find out from him what had happened. He answered a few questions but soon broke off, demanding to know why they could not simply put Stephen into a car and drive him to the Brook hospital. They insisted it would be wiser to wait for the ambulance.

A panicky atmosphere hung over the scene. Duwayne was shouting, asking where the ambulance was, asking if Stephen was alive and why the police had to be there. Stephen's breathing, which a few moments earlier had been strong enough to cause a visible movement of the chest, had weakened. Normally, the police would expect to reach an attack scene at much the same time as the ambulance. PC Gleason consulted with WPC Bethel and decided to drive towards Woolwich to see if there was a problem on the road.

Another police car arrived, bringing another officer, Joanne Smith. She and Bethel spoke to Duwayne, who managed to spill out the essential details. They had been attacked by six white men who used the word nigger; he had told Stephen to run but they had caught him and struck him with something that looked like an iron bar; the attackers had run off down the side road. Duwayne also supplied his own name and address and Stephen's name.

The Taaffes were still crouching beside the unconscious Stephen, praying and offering comfort. "You are loved, you are loved," Mrs Taaffe whispered to him. He had moved his head a little once - Mr Taaffe thought this an effort to breathe more easily - but apart from that he seemed peaceful. Now the Taaffes were concerned that his breathing had ceased altogether, and they called Bethel over. She, too, crouched and put a hand in front of Stephen's mouth. She thought there was a faint breath. She took his pulse, and once again thought she detected something, but later she was to say that, in the excitement of the moment, it may have been her own pulse she felt.

At 10.54pm - four minutes after the first police car and probably 14 minutes after the attack - the ambulance arrived. It had been delayed slightly by a confusion over the location, but the response time was well within the normal range. Geoffrey Mann, the paramedic on board, quickly examined Stephen and found no vital signs: no pulse, no heartbeat, no respiration. Mann and his driver, with a little help from Mr Taaffe, put Stephen on a stretcher and loaded him into the ambulance. When they lifted him, they all saw with horror that his clothing and the pavement beneath were awash with blood. What kind of attack had this been, wondered Mr Taaffe. How was it possible to inflict such damage with an iron bar?

The ambulance left the scene at 11.03pm, with Mann already working to restart Stephen's breathing. Duwayne had wanted to accompany his friend, but was persuaded to follow with WPC Smith in the panda car. With his siren on, ambulance driver Michael Salih headed straight up the hill in the direction of Woolwich and then, at the traffic lights at the crest of the rise, turned left into Shooters Hill Road. Another left took him into the forecourt of the Brook Hospital and to the A&E Department, where a trauma team, forewarned by radio, stood ready. The journey had taken three minutes.

Stephen was swept into Resuscitation Room 1, where many things happened at once: a continuous effort was made to restart his heart by pressing down on his chest again and again; a tube was passed into his windpipe to restore respiration artificially; several attempts were made to insert further tubes into Stephen's veins to replace lost blood, but this proved impossible because so much had been lost that the vessels had collapsed. It was obvious to the nurses and to the surgeon that this dreadful blood loss was not the result of an attack with an iron bar, and as they cut away Stephen's clothes they found two wounds, one in the chest and the other on the shoulder. While the work of resuscitation went on, two members of the team, in surgical gowns, went to find out what had really happened.

Outside they found Duwayne, PC Gleason and Neville and Doreen Lawrence.

Stephen's parents had found out extremely quickly, from an eyewitness, that their son had been attacked. Joey Shepherd had boarded a bus in Well Hall Road, thinking he had witnessed a mere scuffle, from which Stephen had been able to run away. But as the bus passed the spot where Stephen lay, he had realised it might be serious. He travelled on over the hill towards Woolwich. He lived near Stephen, so he alighted by Woolwich Common and walked home, where he told his father what he had seen. Father and son went promptly to the Lawrence home.

Doreen had been tired when she got home from her trip and was getting ready for bed when she heard a knock on the door. At first, she thought Stephen must be home, but then she heard the voices of strangers. Going down to find out who it was, she heard Joey Shepherd explain that he had seen Stephen being attacked at a bus stop near the Welcome Inn on Well Hall Road, but that he did not know how badly hurt he was. Joey's father suggested the Lawrences call the police and ask what they knew. Doreen immediately dialled 999 and was put through to the police, who told her they had no report of such an incident. The call was logged at 10.56pm, just after Geoffrey Mann's ambulance had reached Well Hall Road.

Doreen threw on a coat and she and Neville jumped in the car. Joey had mentioned the Welcome Inn, so they drove there, stopping for a red light on Shooters Hill Road along the way. They must have missed the ambulance at the same junction by seconds. All was quiet near the pub; no police, no crowd. At the bus stop nearby, nothing. In fact, the Welcome Inn is higher up the road; they were still about a quarter of a mile from the scene of the stabbing. Neville turned the car and went to Brook Hospital to see whether they could learn anything there. It was just around the corner and they were there in a few moments; while Neville parked, Doreen ran in. If her son was here, she expected him to be in the casualty waiting area, and when she saw that he was not she was relieved and ready to leave. But when Neville arrived he immediately saw Duwayne, and asked him what had happened. Before he could answer, the people in green gowns appeared, to ask about the injuries.

Duwayne could only tell them what he had seen: Stephen had been hit with something that looked like an iron bar. Neville and Doreen, now gaining their first inkling of the seriousness of their son's situation, stammered out questions. Was it really Stephen in there? What was happening? Could they see him? No, they were told, not yet.

They were ushered into a nearby room to wait. Duwayne joined them, but was too distressed to answer questions. The Lawrences were in torment. "We thought maybe Stephen had been stabbed in his arm or he had cut his hand or something," Neville would later recall. "I was praying that he was not dead. I thought it was just a fight in which he got cut badly ... I don't remember if we talked to each other; we just sat there. All sorts of thoughts were going through my mind. I don't remember how long we were sitting there but it could have been half an hour."

Eventually, the doctor and the nurse returned. Neville saw them coming: "I was thinking, 'Are they coming to tell me that Stephen is dead?'" They were.

Stephen had been stabbed twice: once high up on the chest, cutting downward through artery, vein, nerve and lung wall to a depth of five inches, and once in the shoulder, a jagged wound that also severed a major artery. Given these injuries, there had never been any real hope, but the A&E staff had tried everything they could. When, after 10 minutes of intensive effort, there had been no sign of pulse or electrical activity in the heart, they had abandoned the struggle. Stephen's death certificate was signed at 11.17pm.

The real moment of death, however, had come earlier. He had been stabbed just before 10.40pm and his heart continued to beat for at most another 15 minutes. It is not known exactly when it stopped, but it was probably some time between 10.50pm, when PC Gleason said he detected a faint pulse, and 10.54pm, when Geoffrey Mann found none. Stephen Lawrence's short life had ended in a pool of his own blood, on the cold pavement close to a plane tree on Well Hall Road

Brian Cathcart's book on the Stephen Lawrence case will be published next year by Penguin