'Crimelite' technology allowed DNA stains, previously hidden, to be identified on Helen Scott's clothes
Media playback is unsupported on your device
Video

World's End murders: How DNA caught Angus Sinclair

Angus Sinclair has been found guilty of the rape and murder of Helen Scott and Christine Eadie, and has been given the longest sentence ever handed out by a Scottish Court, 37 years.

The teenagers met Sinclair on a night out at the World's End pub on Edinburgh's Royal Mile in October 1977.

Their bodies were found in the East Lothian countryside the next day.

Sinclair is the first man to be tried following a change in the law abandoning the principle of double jeopardy and allowed a second trial.

BBC Scotland's home affairs correspondent Reevel Alderson looks at how he was caught.

Go to next video: Sinclair is 'dangerous predator'