We have been told at least four different stories about how and when PT/35(b) was found and when it was examined. Let us review the various statements.
A. Lord Boyd 
On 13 January 1989, Detective Constables Thomas Gilchrist and Thomas McColm found a fragment of charred clothing in search sector I, near Newcastleton. This piece of charred grey cloth was bagged, labelled “Charred Debris” and given a reference number: PI/995.
On 12 May 1989, Dr. Thomas Hayes examined PI/995. Inside the cloth, Dr.Hayes found fragments of paper, fragments of black plastic and a tiny piece of circuitry. Dr. Hayes gave to these items the reference number PT/35 as well as an alphabetical suffix to each one of them. The fragment of the circuit board was named PT/35 (b).
B. Richard Marquise (FBI) 
Although it [PT/35(b] had been located early on in the search, the piece of cloth [PI/995]in which it had been blasted was not examined until a year after the attack.
C. The Central Intelligence Agency 
The sequence of events that really changed the foccus to the Libyans occured in the fall of 1989. Months after the plane went down, the Scots discovered a piece of a circuit board from the timer that came from the bomb that destroyed Pan Am 103. A shredded shirt containing the fragment was found by a Scotsman walking his dog after the formal recovery effort had ended. […] This farmer saw this fabric, looked at it, knew, of course, the plane had crashed… and brought it to the attention of the Scottish police. The shirt had been destroyed . However, … the label in the back of the collar had a tag that linked it to Mary’s House…
D. The BKA (BUNDESKRIMINALAMT) 
On 22 January 1990, Scottisch scientists of the Royal Armement Research and Development Establishment (RARDE) found a fragment of a green circuit board lodged in the cuff of a “Slalom” shirt which was identified as “PT 35”, and could have possibly been part of the detonator…
1. THE LOCKERBIE TRIAL by RT. HON COLIN BOYD QC, LORD ADVOCATE, SCOTLAND
2. SCOTBOM: Evidence and the Lockerbie Investigation by Richard A. Marquise
3. CIA’s role in the Pan Am 103 Investigation