oddity in the tracking caused by the Letraset of the template not having been cut quite flush. One thing seems reasonably certain. The scrap of collar and the shirt it was part of was extremely close to the explosion.
The careful logging of the recovered debris shows four separate parts of that same shirt recovered from widely separated locations which form an almost perfect straight-line continuation of the “southern debris trail”.
This all fits perfectly with the known distribution of the falling, wind-swept debris.
Was PT/35b, the infamous printed circuit board fragment, actually lodged in the cloth at that time? It’s impossible to say, but it has not been proved it wasn’t. What has been proved is something altogether different, something entirely unsuspected during the years when the defence teams were poring over the forensic notes and wondering if certain pages might have been added at a later date.
Serious attempts to find out what the fragment PT/35b was began in earnest after it was handed over to Scottish detectives in January 1990.
Physical and chemical analysis carried out at the University of Strathclyde, while policemen patiently telephoned and visited manufacturers of electronic components and suppliers of raw materials, found nothing earth-shattering.The raw materials were unremarkable, used in millions of gadgets and gizmos worldwide.
However, a detailed report dated September 1990 cataloguing the effort noted one particular feature that seemed anomalous. Printed circuit boards have a coating on the circuitry, known as ‘tinning’, applied to make the
components easier to solder. In mass manufacturing this coating is almost
always a tin/lead alloy, however PT/35b had a coating of pure tin. It had been applied in such a way as to suggest this had been done by electroless plating, a method used by amateurs making only a few boards as a hobby.