Police in the Lockerbie frontline

The devastation in Lockerbie was extensive

The bombing of Pan Am Flight 103 just four days before Christmas in 1988 led to one of the biggest police operations ever mounted in the UK.

Here BBC News Online outlines the scale of that operation, conducted by the UK's smallest force, and highlights some of the key events which led to the two accused standing trial in the Netherlands.

The bombing:

The tragedy began to unfold at 1903GMT on Wednesday, 21 December 1988, when the Pan American Boeing 747 Maid of the Seas, en route from London to New York, exploded at about 31,000ft over Lockerbie.

The death toll was high:

• 270 people of 21 different nationalities were killed

• 243 were passengers on the plane

• 16 were members of crew

• 11 were Lockerbie residents.

A further five people on the ground were injured, two of them seriously.

As wreckage rained down on the town and surrounding Dumfries and Galloway countryside the extent of the devastation began to emerge:

• 319 tons of wreckage were scattered over 845 square miles of the Scotland/England border, between Lockerbie and the North Sea

• Just after the explosion a strong reading was recorded at the Seismic Earthquake Centre in Eskdalemuir

• The A74 trunk road was closed and water, electricity and gas supplies were cut.

The immediate aftermath:

Schools in Lockerbie were on holiday at the time of the explosion and on 22 December a temporary incident control centre was set up in the town's academy.

Eleven people died on the ground

The first back-up officers arrived at Lockerbie on the evening of the crash, and the next morning instead of the four officers who would normally have been on duty in the Lockerbie area, there were approximately 1100 police officers and 1000 military personnel.

Their numbers were further swelled by personnel from other rescue and emergency services, local authorities and voluntary agencies as well as civilian volunteers.

On 23 December, 1029 police officers were on duty around Lockerbie and an average of 1043 police were involved on a daily basis during the first week of the operation.

Those numbers dropped off quickly and by week four the number of police involved was down to 109, and by week 47 there were 68 police assigned to the case.

Police staff were boosted by a further 500 people from professional and voluntary organisations to help with:

• The search for victims and wreckage

• The forensic, pathology, medical and radiography services used to start the investigative process.

Extra police were drafted in from numerous forces across the UK, including:

• Strathclyde, Lothian and Borders, Central Scotland and Grampian

• Metropolitan, Cumbria, West Yorkshire, Northumbria and Lincolnshire

• British Transport Police and the Ministry of Defence Police.

The murder investigation:

The murder probe extended through 70 countries, with police visiting 23 of them.

Water and electricity supplies were affected

Outside help for the Dumfries and Galloway force continued until 1992.

The inquiry team was responsible for identifying the victims, interviewing witnesses in various languages and the recovery and packaging of many tons of property.

Despite the many complications and the variety of languages, cultures and judicial systems involved, the inquiry team tried to stick to the principles of Scottish criminal law.

The evidence formed the basis of a report against two Libyan nationals, Adelbaset Ali Mohmed Al Megrahi and Al Amin Khalifa Fhimah, which was submitted to the procurator fiscal.

On 13 November, 1991 an arrest warrant for the suspects was granted at Dumfries Sheriff Court.

A fortnight later the UK and US governments made a joint declaration urging the Libyan Government to disclose all it knew about the crime and to help the investigation.

Wreckage rained down over a huge area

In January 1992 the United Nations Security Council passed Resolution Number 731 which called on the Libyan authorities to help.

Further resolutions were passed at the Security Council in 1992 and 1993 demanding that the Libyan Government hand over documents and comply with the original call for assistance.

In July 1998 the Security Council welcomed moves towards the trial of the two accused before a Scottish Court sitting in the Netherlands.

The UN body also urged all countries, and in particular the Libyan Government, to ensure the appearance in the Netherlands of the two accused.

Later that month Statutory Instruments United Nations High Court of Justiciary (Proceedings in the Netherlands) Order 1998 was passed, which legalised proceedings in Holland under Scots Law.

In September 1998, agreement was reached with the Dutch authorities to host the trial, and in November Kamp Van Zeist, or Camp Zeist, a disused military base, was identified as the site for the Scottish Court in the Netherlands.

Trial details

The two accused are Abdelbaset Ali Mohmed Al Megrahi, 48, and Al Amin Khalifa Fhimah, 44

Pan Am Flight 103 exploded over Lockerbie on 21 December 1988, killing all 259 people on board and another 11 on the ground

The two men deny murder. Charges of conspiracy to murder and a breach of the 1982 Aviation Security Act were dropped

The trial is taking place in a Scottish courtroom at Camp Zeist, in the Netherlands

The case is being heard by a panel of Scottish judges

On 2 April, 1999 the first police team arrived at Camp Zeist and three days later the accused surrendered themselves to the United Nations.

Following an abbreviated extradition process, Adelbaset Ali Mohmed Al Megrahi and Al Amin Khalifa Fhimah were handed over to Dumfries and Galloway police at Camp Zeist that same evening.

They were formally arrested and placed in police custody.

The accused were charged, in line with the original arrest warrant, on 6 April, 1999.

On 18 October, 1999, and after lengthy negotiations, a team of police travelled to Libya to carry out more enquiries.

On 14 April, 2000 the two accused were committed for trial by the sheriff principal of south Strathclyde and Dumfries and Galloway, sitting at Camp Zeist.

On 3 May, 2000 the trial began and some eight months later was completed on 18 January, 2001.

The agreement by the Libyan Government to release the two accused for trial in the Netherlands meant the start of a detailed planning and preparation operation.

Police have been drafted in from across Scotland

Under the management of Dumfries and Galloway police, officers from all over Scotland started the process of converting the former US air base into a high security site housing a prison and the court building.

The facilities also house the enormous amount of behind the scenes activity which an event of this scale generates.

Officers from all eight of Scotland's police forces have volunteered for duty at Camp Zeist.

Police with specialist skills, such as a firearms capability or expertise in search work, have been involved.

Superintendent site commanders have carried out six month long tours of duty with other staff seconded for a three month tour. All officers have worked a 12-hour shift pattern.