Colin Pearson, who was 12 at the time, gave a statement to police about visiting the Old Exchange Building in Hendon, Sunderland, where Nikki s body was found.
Prosecutors say a comparison of the two images is compelling evidence that David Boyd was the man who lured Nikki away from her home and beat her with a brick before stabbing her.
Nikki Allan: Jurors shown footage of 'final tragic glimpse' of schoolgirl, 7 itv.com - get the latest breaking news, showbiz & celebrity photos, sport news & rumours, viral videos and top stories from itv.com Daily Mail and Mail on Sunday newspapers.