[104-10209-10019.pdf — page 53]
# 14-00000Attachment to GTA-15927dated 22 November 1960SUBJECT: Report on Testing of Letters for SWREFS: (1) OFPA-55220, 4 November 1960(2) GTA-15921, 8 November 1960(3) FRAN 73231.  The purpose of this report is summarize the laboratory work done on two letters transmitted to us originally as attachments to Reference #1. For identification purposes in this report we shall refer to the letter postmarked in Philadelphia as Letter #1 and the one postmarked in the USSR as Letter #2.2.  In order to facilitate a better understanding of the results some interpretative data on the tests performed is included.3.  Because of the requirement that the letters be left in good condition to permit their delivery to the addressee, the initial examination consisted of the customary visual and U.V. inspection (including long wave and short wave), and the so-called KEYNOTE test. This latter test has only recently been introduced and constitutes the most formidable test known to us against SW. It was by means of this test that the presence of SW in letter #1 became apparent. In the application of this test a portion of the SW is actually physically lifted from the item being tested and subsequently through a process involving both chemical and physical reactions, the SW is made visible. The degree of visibility varies from completely negative results to completely legible ones. According to the technician who performed this test the results obtained with Letter #1 were not quite legible, but definite enough to permit checking to establish that they were not due to the visible ink of the letter. The time interval during which this particular detection is observable lasts but a few minutes which the technician used to verify that he was detecting SW and not visible text. By the time he called in his two colleagues the reaction had progressed to the point that only one of these technicians was able to observe the SW. Thus the operator and one other technician saw the SW.4.  At this point the letters were returned to Paris with Reference #2 which reported "definite traces of SW" in Letter #1.5.  Before giving an account of the work done during the second phase of the investigation. (i.e., after the letters were returned to the laboratory for development) it should be pointed out that the KEYNOTE test, though an extremely effective test for the detection of SW, does not identify the system involved. Complete development of the secret message under these circumstances would have been almost impossible. The only alternative available to the chemist, and the one he followed in this particular case, is to proceed with a series of chemical tests applied directly to the document under investigation. These tests are applied in sequence, one after the other, each requiring for its execution that a portion of the page be sacrificed. It is therefore important that those tests affording the greatest probability of developing the SW be applied first; thus if and when, a test is found capable of developing the ink, the remainder of the page (i.e., the portion not affected by previous chemical applications) is treated with it.SECRETKAPOK![DESENSITIZED]per CSM 43-28