A tweet from British-Syrian blogger Razan Saffour about the photographer was retweeted more than 7,000 times. Daniel Hannan, the Conservative MEP and author, implored us to remember his name.
Al-Rayess was first mentioned in this Al-Arabiya story published on 21 July 2014 in Arabic only.
Charlie Cooper of the Quilliam Foundation, who looked at the article for i100 , explained it states that he was a Syrian journalist who was executed by Isis in July, six weeks before the murder of another American journalist, James Foley.
His body was found alongside seven bodies of fighters from the Army of Islam, another jihadi group.
Mr Cooper told us that while it would be very difficult to verify the story, "I've no doubt the Islamic State would have killed other Syrian journalists".
He added: “It's very important that the media treats all of these atrocities responsibly and equally to win the war against the Islamic State.”
Saffour, whose tweet about Al-Rayess went viral, translated the article for i100.
This is what it says:
"Yesterday, on Monday, the city of Douma buried the photo-journalist Bassam A-Rayess who was field executed by Isis in Eastern Ghouta.
In addition, seven bodies belonging to soldiers from 'The Army of Islam - Damascus' brigade were found on the outskirts of the city of Douma; they too had been executed.
Several revolutionary and Islamic brigades have declared war on Isis, accusing them of being behind the last two bomb explosions in Douma."