Islamic State fanatics release sickening new footage of mass executions. Included are horrifying scenes of a child executing several prisoners. The 22-minute film shows wholesale slaughter of Iraqi military cadets. It was filmed at last year's notorious Speicher massacre, in Tikrit, Iraq. Men are machine gunned in mass graves, while others are shot in the head. WARNING GRAPHIC CONTENT Harrowing new footage has emerged of a young boy executing prisoners on the banks of the Tigris River, amid one of the biggest massacres ever committed by Islamic State fanatics. Filmed during the ISIS killing spree in Tikrit last year,...