RECORDS of sexual offences committed in Scotland by Robert Black which could have alerted police to the danger he posed before he became a serial killer were lost, The Herald can reveal.

It has also emerged that Black, who was yesterday found guilty in Northern Ireland of the murder of nine-year-old Jennifer Cardy in Ballinderry, County Antrim, in 1981, was a suspect in the original investigation 30 years ago but police found no reason to arrest him.

Black, 64, who was sentenced to life imprisonment for killing Jennifer, has now been found guilty of four child murders. He was convicted in 1994 over the deaths of Susan Maxwell, Caroline Hogg and Sarah Harper.

Police have revealed that he is thought to be responsible for at least another four child murders in the UK and possibly others abroad.

The Herald can disclose that, tragically, records of Black’s teenage conviction for sexual offending had gone missing, and that meant he was not connected to later murders, nor caught for the murder of Jennifer, before he abducted and killed other children.

Yesterday’s conviction was met with relief by Jennifer’s family, who said the trial had been an “absolutely horrendous” experience.

Jennifer had left her home to cycle a short distance to meet a friend. Her body was found at McKee’s Dam near Hillsborough, six days after she disappeared. Black had sexually assaulted and killed her.

Former Chief Superintendent Andrew Watt was the senior investigating officer on the UK-wide investigation launched in 1990 after Black was caught red-handed abducting a six-year-old girl in the Borders village of Stow.

He said: “As part of the investigations, we had looked at everyone across Scotland who had been convicted of sexual or similar offences.”

“Black had been convicted of a minor sexual offence in the old Argyll and Bute police area but the records had gone missing. It was during this time that there was a great deal of reorganisation in the police and courts, and offices were moved around. When we asked for records earlier he did not come up against the records of those convicted of sexual crimes. They looked at him but he had no record.

“It was not until after 1990 that we discovered he did have a conviction. When he was arrested [in 1990] we did a tremendous amount of work looking into his background, and a witness told an inquiry officer about his upbringing in care homes. The conviction in Argyll and Bute was for a sexual offence when he was a teenager. Police records were kept but these were lost in the re-organisation of the 60s and 70s. DNA was not really used. It was a different era.”

Abe Stockport, a former detective sergeant with the Royal Ulster Constabulary who worked on the original investigation into the death of Jennifer, told The Herald that Black was one of a number of long-distance drivers looked at by police three decades ago.

“There was no DNA or anything at the time but Black was a suspect because we were looking at long-distance lorry and van drivers,” he said.

“There was a lay-by along the Belfast-Newry road where lorry drivers would sleep for the night and he was seen there but there was just nothing we could do. We had nothing on him. At that stage the petrol receipts [later used to tie Black to the areas where Jennifer was last seen] were not available and there were hundreds of other suspects.

“We looked at all those in the areas with convictions for sexual offences. We worked on it for months and cleared up a lot of other local crimes as a result. It was a difficult time. Each officer might have been dealing with 10-15 murders at a time on their own.

“There was a team of 12 of us. I have dealt with throat-cutting cases, terrible violence, but this is the worst case. The memory of it never left me.”

Black, from Grangemouth, who is in Wakefield prison, has now been convicted of kidnapping and murdering four children in the 1980s, but officers think he is responsible for at least four more deaths.

Black kidnapped Susan Maxwell, 11, from Coldstream Bridge on July 30, 1982, murdered her and dumped her body near Loxley, Uttoxeter.

Caroline Hogg, five, was falsely imprisoned by Black. He lured her away at Portobello, Edinburgh, on July 8, 1983, murdered her and

dumped her body at Twycross,Leicestershire. He kidnapped Sarah Harper, 10, on March 26, 1986, murdered her and dumped her body in the River Trent near Ratcliffe-on-Soar, Nottinghamshire.

He also kidnapped Teresa Ann Thornhill, then 15, from Nottingham, in April 1988. Teresa survived to give evidence against Black in the 1994 trial.

Mr Watt said: “We estimate that he killed eight children in total. The plan was to secure the conviction for the young girl at Stow and then investigate the other disappearances of children in greater depth. It is so terrible for the families. It must be on their minds all of the time.”

He added: “We also learnt that he had been frequenting a caravan in France. Two of my officers went across there. We had been told to expect trophies [mementos from the victim] by the FBI, but we didn’t find anything. We know that he was also going to Holland as that is where most of his child pornography came from. It was the biggest collection of child pornography that had ever been found at that time, according to the Met.”

The four other cases are thought to include Genette Tate, abducted when she was 13 in 1978 at Aylesbeare, Devon, and still missing; Christine Markham, aged nine when she was abducted in May, 1973, at Scunthorpe and never found; April Fabb, 13, who vanished in 1969 while cycling in her home village of Metton in Norfolk, a county Black visited regularly; and Patricia Morris, 14, abducted in June, 1980, at Hounslow, London, and found murdered.

Detective Sergeant Willie Davidson, of Lothian and Borders Police major crime unit, said: “There was no doubt he travelled in Europe, and who’s to say that if the same scrutiny was put into Europe that there may not be other cases there? I find it hard to believe he could be driving across Europe and that the opportunity did not present itself. He talked of getting a ‘rush of blood to the head’ in Stow, and it seems likely that happened quite frequently.”

A spokesman for Europol said they would require a member state to ask them to investigate Black’s movements across Europe.

A CPS spokeswoman said it was not looking to re-open the other cases at this time.