Jennifer Cardy did not like to be late. Punctuality was one of the nine-year-old's qualities and so it was as she prepared to cycle to her friend's house on that sunny August day 30 years ago.

She had just finished a lunch of poached eggs with her brothers Philip and Mark and, nursing her baby sister Victoria, asked her mother Patricia to wind up her red watch.

"She was a very thoughtful little girl and her time to leave was always 1.40pm because she liked to get to her friend's house for about 2pm," Mrs Cardy told Robert Black's trial.

"Most importantly, she liked to be back in time for Jackanory and for that reason she always checked her watch."

Unsurprisingly, her mother can recall that day - Wednesday August 12 1981 - in vivid detail. "I can well remember what Jennifer was wearing," she said.

"It was her favourite T-shirt, a white T-shirt trimmed with red round the neck and on the T-shirt were red strawberries."

The schoolgirl was off on her new red bike, bought for her birthday two weeks before, to visit her friend Louise Major, who lived a mile and a half away at the other end of the Co Antrim village of Ballinderry.

A fortnight earlier the pair had spent a fun day together watching the wedding of the Prince of Wales and Diana Spencer on television.

Louise would later reveal that after once seeing a TV programme about someone who got into a strange car and was abducted, Jennifer vowed she "would never do that".

When Jennifer did not return on time, her mother knew something was wrong. As it turned out, the girl never reached Louise's house.

A frantic search of the area found no trace of her. Her father Andy called the police around 9pm and the operation escalated.

Then, just before midnight, two local men scouring the area in their van spotted Jennifer's bike lying in a field beside the Crumlin Road, just over a mile from her home. It had been thrown over the hedge. The stand was in the downward position, suggesting that the unsuspecting Jennifer had stopped to talk to her abductor.

The incident took place as violence raged in Northern Ireland. The IRA hunger strikes were going on at the nearby Maze prison and murders and bomb blasts were part of everyday life.

But divided communities united as seldom before in the search for little Jennifer, as hundreds joined in the attempt to find her. It would be six days before she was finally discovered.

Two duck hunters spotted her body floating among weeds in a dam, known as McKee's, behind a layby on the main A1 dual carriageway at Hillsborough, Co Down, around 15 miles from Ballinderry.

Her watch had stopped at 5.40pm. Ultimately, that helped prove she was dumped by her killer just hours after she pedalled off from home.

Nine days into his trial at Armagh Crown Court, Robert Black's long criminal record was outlined to a stunned jury. They heard the man in the dock had been found guilty of three child murders and an attempted abduction at Newcastle Crown Court in 1994.

Those convictions only added to a series of other offences against young girls from his dark past.

In often unpalatable detail, all Black's previous crimes were outlined to the court during the Armagh trial.

Black's crimes

1982 - Susan Maxwell - Murder

The 11-year-old schoolgirl lived on her family's farm near the village of Cornhill on Tweed on the English side of the Scottish border.

On Friday July 30, a glorious sunny day, she arranged to play tennis with a friend two miles away, just over the border in the town of Coldstream.

She got a lift there and had persuaded her mother Liz to let her walk back - the first time she had done so on her own.

Her game finished at 4pm and Susan, wearing a yellow T-shirt and shorts and carrying her racquet and a flask of juice, was seen crossing the bridge back into England over the River Tweed on her way home.

But then she vanished.

A huge police search operation failed to find any trace of her. Two weeks later, her body was found 264 miles away lying a ditch at a roadside lay-by just outside Uttoxeter in the Midlands. Still wearing her T-shirt and shorts, her pants had been removed, folded and placed under her cheek.

Work records showed that Black had been travelling between Edinburgh and Newcastle on the day Susan vanished and that he would usually return to London through the Midlands, where he would visit a friend. The friend lived in Donisthorpe - 20 miles from the lay-by where Susan was found.

1983 - Caroline Hogg - Murder

Five-year-old Caroline, from Portobello near Edinburgh, had spent most of Friday July 8, 1983, at a friend's birthday party.

She wore a princess dress - one she loved so much that her parents let her keep it on for the rest of the day.

That evening back at her home on Beach Lane, she was allowed out to play for five minutes in the school grounds opposite her house.

Caroline was forbidden to go any further on her own, to a nearby play park or the seaside promenade. Her mother went to call her in after about half an hour but there was no reply.

It emerged that a boy had spotted Caroline in the play park she was not allowed to go to. She was on the swings. The child also noticed a "scruffy looking man" sitting on the promenade watching her play.

Another child had seen her walking towards the town's funfair, Fun City, hand in hand with an unknown man. A teenager who worked in the amusements saw the man pay for her to ride the roundabout.

After that there were no more sightings. Caroline, too, had disappeared into thin air.

Ten days later, again in the English Midlands, a girl's body was found. It was Caroline. Badly decomposed, the dead child was completely naked - again suggesting a sexual motive.

It later emerged that Black, who used to swim in Portobello as a teenager, had been back in the town the day Caroline disappeared, making a delivery. Petrol receipts showed the van driver had filled up at Stafford on his way back to London - the service station being ten miles from where Caroline's body was found.

1986 - Sarah Harper - Murder

Ten-year-old Sarah lived in the working class area of Morley in greater Leeds. On the evening of Wednesday March 26, during her Easter holidays from school, she was sent on an errand to the corner shop by her mother.

It was a rainy night. Sarah pulled a blue anorak over her burgundy jumper, picked up two empty pop deposit bottles to reclaim some pennies and set off.

The shop keeper remembers her calling in, buying a loaf of bread for her mum and, with the money from the bottles, two packets of crisps. She was last seen heading down a short alleyway on her way home.

Three and a half weeks later, a man walking his dog along the River Trent at Wilford near Nottingham saw Sarah's body floating in the water.

Her anorak was gone, as was her skirt. Better preserved than the other two girls as her body had been in water, a post-mortem examination revealed she he had been subjected to a violent sexual assault. The cause of death was drowning, with tests suggesting she was still alive when dumped in the river, albeit possibly unconscious.

Robert Black made a delivery in Morley the evening Sarah disappeared. A return trip to London via the River Trent would have seen him take the same exit off the M1 motorway he used when visiting his friend in Donisthorpe.

1988 - Teresa Thornhill - attempted abduction

Teresa was 15 but looked much younger - she was only 4ft 10in.

On the evening of Sunday April 24, she was walking through the Radford area of Nottingham with a friend, Andrew Beeston. It was then they spotted a blue Ford Transit van driving suspiciously.

After she and Andrew went their separate ways at a crossroads, Teresa again saw the vehicle, this time parked up in front of her on Norton Street. The driver got out and opened the bonnet and shouted at the girl.

Feeling uneasy, she crossed to the other side of the road. Again the driver shouted out.

"Can you fix engines?" Robert Black barked. He grabbed her from behind, enveloping her in a tight bear hug, and tried to drag her over to his van. In her efforts to escape, Teresa bit Black on the hand and arm and knocked off his glasses.

He thrust his hand over her nose and mouth and tried to push her into the van door. But the schoolgirl resisted, wedging her feet up on either side of the door frame and refusing to go in. "Get in, you bitch," Black shouted.

Teresa later told police: "I was fighting for my life." As the struggle continued Teresa's friend Andrew, who had heard her cries for help, came running to the scene.

Black finally let go and the two of them ran away as the killer sped off in his van.

During his trial it emerged that Black had made a delivery just 500 yards from the scene of the attempted abduction earlier that day.

Further convictions

1990 - Stow - abduction and sexual assault

Black was finally caught when he was stopped by police in the Scottish village of Stow with a six-year-old girl hooded, gagged, bound and stuffed in a sleeping bag in the back of his van.

He had snatched her from the village 20 minutes earlier and had taken her to a lay-by to molest her. Black was sentenced to life imprisonment for the kidnap and attack.

But while Black got used to jail, detectives were methodically examining his past - an exercise that would eventually connect him to the three unsolved murders and the attempted abduction.

1963 - Greenock, Inverclyde - lewd and libidinous behaviour

At the age of 16, Black lured a seven-year-old girl from a play park to a disused air raid shelter after promising to show her a box of kittens. He choked her until she fell unconscious and then molested her.

Black left her for dead. She was later found wandering on her own, in tears and bleeding. Remarkably, Black was not incarcerated for the crime after being found guilty of only "lewd and libidinous" behaviour.

1966 - Kinlochleven, West Highlands - indecent assault

After the Greenock incident, Black returned to the place where he was raised only to again target a young girl, this time the daughter of a couple he was lodging with.

Entrusted to baby-sit the seven-year-old, Black instead took the opportunity to repeatedly violate her. He was convicted of three counts of indecent assault and sent to borstal at Polmont near Falkirk for a year.

Robert Black: profile of a serial killer

Evidence: the crucial petrol receipt

The lawyer: ending unfinished business

Robert Black guilty of fourth child murder