Mr. Latona. Yes; I would say that is true, considerably so. We have more success with silver nitrate than we do with the iodine fumes.
The reason we use both is because of the fact that this material which is exuded by the fingers may fall into one of two main types—protein material and salt material. The iodine fumes will develop protein material. Silver nitrate will develop the salt material.
The reason we use both is because we do not know what was in the subject's fingers or hands or feet. Accordingly, to insure complete coverage, we use both methods. And we use them in that sequence. The iodine first, then the silver nitrate. The iodine is used first because the iodine simply causes a temporary physical change. It will discolor, and then the fumes, upon being left in the open air, will disappear, and then the color will dissolve. Silver nitrate, on the other hand, causes a chemical change and it will permanently affect the change. So if we were to use the silver nitrate process first, then we could not use the iodine fumes. On occasion we have developed fingerprints and palmprints with iodine fumes which failed to develop with the silver nitrate and vice versa.
Mr. Eisenberg. Now, Mr. Latona, looking at that bag I see that almost all of it is an extremely dark brown color, except that there are patches of a lighter brown, a manila-paper brown. Could you explain why there are these two colors on the bag?
Mr. Latona. Yes. The dark portions of the paper bag are where the silver nitrate has taken effect. And the light portions of the bag are where we did not process the bag at that time, because additional examinations were to be made, and we did not wish the object to lose its identity as to what it may have been used for. Certain chemical tests were to be made after we finished with it. And we felt that the small section that was left in itself would not interfere with the general overall examination of the bag itself.
Mr. Eisenberg. That is, the small section of light brown corresponds to the color which the bag had when you received it?
Mr. Latona. That is the natural color of the wrapper at the time we received it.
Mr. Eisenberg. And the remaining color is caused by the silver nitrate process?
Mr. Latona. That is correct.
Mr. Eisenberg. Does paper normally turn this dark brown color when treated by silver nitrate?