The method known as the 'INK H' technique is quite simple. First you select the letters you intend to use as the carriers and write them down in ink, next insert your code letters into the inked letters in pencil and then write over the lot once more in ink. The pencil letters are not visible to the naked eye.
The next step is 'develop' the hidden code and this is done by soaking the paper containing the inked and hidden pencil letters in a strong bleach. The result is that the bleach removes the ink leaving the revealed pencilled code.
The method can be used for hiding micro letters and larger letters. Readers of this blog would know that the SM code was recovered using UV light which revealed indentations whch turned out to be the code letters. These indentations showed up as the darker markings behind the overwriting in the image above as done by the SA Police. I was able to identify numerous micro letters written within the larger letters because of the indentations, sadly we do not have the original document and this post tells us that it is highly unlikely that we will ever recover that.
This is an exciting development and one that provides us with another extremely strong indication that this is an Espionage case.
More to follow.