Now, video footage has emerged showing the man encouraging the crowd before the massacre.
The video which surfaced on Monday, October 3rd, shows the former militant shuffling hostages in Palmyra into formation for a public execution, then alongside his fellows joining hands, chanting in unison.
The 28-year-old has consistently maintained since his July 2015 arrest that he was never an active participant in the violence during his 4-month stay in Syria, insisting that he had been a bystander in propaganda videos and had never even completed his military training.
In the footage uncovered by German broadcaster ZDF, Harry S. is also depicted encouraging the crowd to cheer shortly before the men are summarily shot.
Before damning revelations, Harry has regaled the Humburg court where he is currently on trial with harrowing stories that made him become disillusioned with IS and wish to return home to Germany.
"I witnessed stonings, beheadings, shootings, hands chopped off and many other things," he said in an interview before the trial. "I've seen child soldiers, 13-year-old boys with explosive belts and Kalashnikovs. Some boys even driving cars and involved in executions," he added.According to the Washington Post, the ex-jihadist's lawyer Attorney Udo Würtz appeared just as surprised as the public to learn that Harry S. had been less than truthful when he said "stood on the side" of the violence and "said no to the killing" when other militants suggested they shot the hostages.
Even before his arrest, Harry S. was well known to authorities in the city of Bremen, having committed a number of petty crimes in his teens before eventually robbing a super market. After a few years of living in London and converting to Islam, he was arrested in Germany in 2012 for failing to pay probation fines. He spent a brief stint in prison where he told Radio Bremen he was radicalized by fellow inmates.
Official estimates suggest that around 870 Germans have traveled to Syria or Iraq to join Islamic extremists. According to ZDF, around 270 have returned.
Watch the video below
Video credit: The Washington Post