It’s a case of human shrapnel.
My eye was penetrated by a piece of the bomber’s shin bone. SURVIVOR
On the morning of Thursday, 7 July 2005, four British Islamist men detonated four bombs, three in quick succession aboard London Underground trains across the city and, later, a fourth on a double-decker bus in Tavistock Square. As well as the four bombers, fifty-two civilians were killed.
The image combinations have been created from public domain photographs; fifty-two images of the victims plus four images of the bombers.
The titles (eg 1+4) reflect the fact that two groups ( victims, terrorists) are simultaneously separated (by ideology and role) and joined (in death/by explosive force).