Mr. Latona. Well, an effort was made to remove as much of the powder as possible. And then this was subjected to what is known as the iodine-fuming method, which simply means flowing iodine fumes, which are developed by what is known as an iodine-fuming gun—it is a very simple affair, in which there are a couple of tubes attached to each other, having in one of them iodine crystals. And by simply blowing through one end, you get iodine fumes.
The iodine fumes are brought in as close contact to the surface as possible. And if there are any prints which contain certain fatty material or protein material, the iodine fumes simply discolor it to a sort of brownish color. And of course such prints as are developed are photographed for record purposes.
That was done in this case here, but no latent prints were developed.
The next step then was to try an additional method, by chemicals. This was subsequently processed by a 3-percent solution of silver nitrate. The processing with silver nitrate resulted in developing two latent prints. One is what we call a latent palmprint, and the other is what we call a latent fingerprint.
Mr. Eisenberg. Can you briefly explain the action of the silver nitrate?
Mr. Latona. Silver nitrate solution in itself is colorless, and it reacts with the sodium chloride, which is ordinary salt which is found in the perspiration or sweat which is exuded by the sweat pores.
This material covers the fingers. When it touches a surface such as an absorbent material, like paper, it leaves an outline on the paper.
When this salt material, which is left by the fingers on the paper, is immersed in the silver nitrate solution, there is a combining, an immediate combining of—the elements themselves will break down, and they recombine into silver chloride and sodium nitrate. We know that silver is sensitive to light. So that material, after it has been treated with the silver nitrate solution, is placed under a strong light. We utilize a carbon arc lamp, which has considerable ultraviolet light in it. And it will immediately start to discolor the specimen. Wherever there is any salt material, it will discolor it, much more so than the rest of the object, and show exactly where the latent prints have been developed. It is simply a reaction of the silver nitrate with the sodium chloride.
That is all it is.
Mr. Eisenberg. Do you frequently find that the silver nitrate develops a print in a paper object which the iodine fuming cannot develop?