Kim Longinotto tells the revealing story of the courageous Italian photographer and photojournalist Letizia Battaglia, now 84, who became one of Italy’s most important social historians with her work photographing the brutal reality of the mafia and their victims in Sicily.

Her images helped to galvanise public opinion against the mobster bullies in the 1990s, and bolstered Italy’s failing political and judicial will for gangster “maxi-trials”, just by persistently proclaiming the reality from which people preferred to look away – the grisly nightmare of corpses in the street, covered in blood. And her pictures exploded the insidious, sentimental myth that mafiosi only ever killed each other, leaving civilians untouched.

Her most horrifying pictures were of dead children. The fact that she was a woman probably helped her to get the pictures: she could interpose herself in a stomach-turning and dangerous situation of macho violence and its aftermath in a less obtrusive and less inflammatory way.

Her photographs are like very bad dreams and simply looking for any period of time at dead bodies is a very strange experience. With some of the shots, it is impossible to avoid the weird feeling that they are not really dead, that death can’t look exactly like this, that these people are sleeping, or play-acting – and doing so in an oddly unconvincing way, in elaborately contorted positions covered in blood.

It’s only after a while that you realise that a crime-scene photo, for all that it is shocking and transgressive, is probably the only time that you will look at the image of a real dead body. This is death, the photo seems to say, and it is waiting for all of us, mafia victims and everyone else.

• Shooting the Mafia is released in the UK on 29 November.