WHICH GUN?

Evening Star, Issue 19781, 3 February 1928, Page 6

WHICH GUN?

IDENTIFYING MURDER BULLET PHOTOGRAPHS TELL One of the greatest obstacles in the solving of murder mysteries is the difficulty of identifying a bullet fired from a particular weapon. But it is possible (says the Sydney ‘Sun’) that before long there will be in general use in Australia a new method of identifying a missile with the weapon from which it has come.

This would have as far-reaching an effect on crime and criminals as that which followed the introduction and acceptance by the courts of the fingerprint system. English experts have been at work on it. So have Australian. One method of identification is now being worked out and perfected by a young Australian, Mr W. E. Bassett, a demonstrator in the physical laboratory of Melbourne University. Were an analysis to he made of all the unsolved murder cases of the past ten years it would probably be found that in many of those in which the murderers used firearms, tho detectives found themselves up against a blank wall, because of their inability to connect the bullet which killed tho victim with the particular suspect upon whom they were endeavoring to fasten the responsibility for the crime. A typical case of this kind is one in which the person towards whom the finger of circumstantial evidence points _ is found to he armed at the time of his arrest. Were it possible to say definitely that a bullet or bullets extracted from the body of the murdered man had been fired from the weapon belonging to the suspected individual, obviously it would be strong and valuable evidence against him. But at present the furthest advance which can be made in this direction is to show that the calibre of the missile and weapon coincide with each other, which, of course, is remotely situated from proving guilt in tho minds of. the average jury of commonsense citizens, who, naturally and rightly, would demand something more convincing. The author of the new system obtained bis first hint as to its possibilities when during the war ho was 'engaged in making tests ior the British Government on the strength of the steel used in the manufacture of various types of service rifles and revolvers. BULLET'S INDIVIDUALITY. To carry out these tests properly it was necessary for him to make a large number of microphotographs, whose object was to show the condition of steel barrels after a certain number of shots bad been fired from them. In doing so, ho was struck by the fact that every barrel, without exception, whether of rifle or revolver or automatic pistol, exhibited a specific kind of individuality in the interior markings of its, rifling, and that this individuality was transmitted to_ the bullets which had passed through it. At the time, however, the pressure of bis ordinary official duties prevented him from following up the hint so obtained, and it was not until the war had been over for some years that be bad the leisure to devote bis attention to the idea. By then he had returned to Australia, and was again engaged at the university. When, eventually, be again turned his mind to the matter he found that the markings in question were even more characteristic of tho barrel from which they bad been fired than he bad at first thought. The initial difficulty encountered was that of photographing the interiors of the barrels, but after some experimenting he at length devised an ingenious method, based upon an arrangement of mirrors and reflectors, by which this could be done. DEFINITE LINES. This step having been accomplished, he,, next set about examining the bullets from the barrels and the comparison of photographs of their markings with photographs of the markings of the riflings inside the barrels. The working out of a satisfactory method of making photographic records of the bullets was nearly as difficult to accomplish as had been the first step, but eventually it was solved, again by the use of mirrors so placed that they revealed practically the whole outside surface of the bullet when it stood upon a small stand in their midst. The picture so obtained, both of the bullets and of the barrel interiors, when developed somewhat resembled those photographs one sees.of the spectrum analyses of gases and vapors. They were long, strip-like ones, with the markings running vertically through them, these varying from in-finitesimally-thin lines to to distinguished only with the aid of a power-

fnl magnifying glass, to fairly wide bands.

But tlie important thing about them was that in every instance, when a comparison was made between the photograph of a bullet and that of the interior of the weapon Irom which it had come, there was found to be an exact correspondence between them. So definite was it that even lines which could be picked out in the one only by means of a careful examination, wore discovered to he represented by exact counterparts in the second picture. What might be termed extraneous markings, such as those caused by the presence of slight blemishes in the metal of the gun-rifling, were also faithfully reproduced in the missiles.

In order to facilitate ilic comparison of the photograph of the bullet-mark-ings with that of the barrel-markings, the pictures were divided into small squares made by ruling linos at right angles to each other, at a distance of about half an inch apart, so that they resembled the maps used for artillery fire during the war. Each square was then carefully examined, and compared with the one corresponding with it on the other record, with the. result that it was possible to say instantly which bullet had come irom which barrel. And since, in the majority of examples, the lines and markings wore frequently numbered by the hundreds, the most remote possibility of chance coincidence was removed, .for it might happen that two or three in the one could agree with the same number in approximately the same position in the other, it was altogether outside the bounds of reasonableness that this could occur with so many. The svstem is not entirely a new *ne, for'in the past several efforts have been made to devise such a method_ of comparison for use in cases in which it is desired to establish the fact that a bullet has been fired from a certain weapon, and for some years Scotland Yard, the headquarters of the London detective force, has employed a plan by which a “control ” bullct from the rifle or revolver under examination is compared with the bullets recovered from some other source, such as the body of a murdered man or the plaster of walls in which the missile was lodged. But evidence on these lines has never yet been put before a jury. The Australian method, however, looks like developing into a system definite enough to.be brought into the courts.