Shearer was appointed on 24 April 2007,[2] in succession to his predecessor David Strang who was made Chief Constable of Lothian and Borders Police.

On 21 December 1988, Pan Am Flight 103 exploded midair as a result of a bomb on board, and the wreckage crashed in the town of Lockerbie, within the police area of Dumfries and Galloway Constabulary.

Eleven townspeople were killed in Sherwood Crescent, where the plane's wings and fuel tanks plummeted in a fiery explosion, leaving a huge crater.

The subsequent police investigation, led by Dumfries and Galloway Constabulary, was the largest ever mounted in Scottish history and became a murder inquiry when evidence of a bomb was found.

Abdelbaset al-Megrahi was jailed for life in January 2001 following an 84-day trial, which was held at Camp Zeist in the Netherlands, but under Scottish law.