It was a commonly held belief throughout the latter half of the nineteenth century, that the last image seen by the eyes of a dying person would be ‘fixed’ on the retina for a considerable period of time. Therefore, if a murdered person’s eyes could be reached without delay, the culprit could be identified from the retinal image.

This seems to have been a popular belief, which resurfaced occasionally throughout man’s history, but the earliest specific suggestion that such images could be photographed for criminal investigations was made by William H Warner, a prominent British photographer of the 1860s.

In April 1863, a young woman, Emma Jackson, was murdered in St. Giles, London. Warner immediately sent a letter to Detective – Officer James F Thomson at the Metropolitan Police Office, Scotland Yard, informing him that: “If the eyes of a murdered person be photographed within a certain time of death, upon the retina will be found depicted the last thing that appeared before them, and that in the present case, the features of the murderer would most probably be found thereon.” Scotland Yard took Warner’s suggestion seriously [stating that] photographing the eyes of a murdered person “is of the greatest importance”. He [Thomson] was obviously conversant with the idea long before Warner’s letter; stating that he had conversed with an eminent oculist four years earlier, and was assured that, unless the eye was photographed within twenty-four hours after death, no result would be obtained: “The object transfixed thereon vanishing in the same manner as an undeveloped negative photograph exposed to light.”

Thomson did not photograph the eyes of Emma Jackson… because she had been dead for forty hours before Thomson saw the body. Her eyes were closed, and she was already buried by the time Warner’s letter arrived.

In 1887 the whole issue was revived. The spark which set off the blaze of speculation was not a personal anecdote (by Warner), which had instigated the reports ten years earlier, but a series of carefully controlled experiments by two prominent and much-respected scientists. Late in 1887, Professor Franz Boll discovered the fact that the external layer of the retina possesses in all living animals a purple colour. This purple surface, he found, bleached on exposure to light but regained its original colour in the dark. Like pure silver iodide, an image would be impressed upon it by the agency of light and if placed in a dark room the image would disappear, and the surface was again ready to receive a second image. This purple colour, which Boll called shepurpur (see purple) [also known as rhodopsin], vanishes immediately after death.

These experiments in the ‘photographic’ sensitivity of the retina were confirmed and extended by Willy Kuhne. Kuhne found that the purple colour did not disappear immediately after death but if kept in a dark room it would remain sensitive for twenty-four hours. In other words, it was light, not death, which rendered the retina insensitive. However, the retina was only re-sensitised after light-bleaching when attached to the back of the eye. Kuhne removed a rabbit’s eye and lifted a corner of the retina. The colour of this flap rapidly bleached but as soon as the flap was replaced, the purple colour was restored; so that: “…the eye carries with it a living substance which has the power of re-sensitizing the photographic film whenever such a process becomes necessary”. It is the bleaching of the purple, by the action of light, which produces an: “ actual photograph… which can be fixed and preserved.” Kuhne called these images ‘optograms’.

As might be expected, the photographic press was exceedingly interested in these tests and was quick to point out the analogy between the eye/retina and camera/emulsion: “ That photo-chemical processes take place in the retina is a matter, therefore, beyond all doubt, and photographers to a man cannot but feel deeply interested in the analogy shown to exist between the eye and the camera he uses every day.” The writers were equally quick to see the connection between these experiments and ‘that old canard’ of the murderer’s image in the eye of his victim. Such a discovery – as the authors of it point out – may lead to the supposition that: there may be something, after all, in those stories of which we frequently hear, of images being visible in the eyes of persons after death, of the retina of murdered men, for instance, showing plainly the image of those who slew them…”

First published in Luna Cornea numero 10 1996 © Bill Jay