The chronology of PT/35(b): 02/03/1992 (Update)

2 March 1992 (Linsdel/Rawlings/Walker – see also 9 March 1990)

According to their HOLMES statements, by prior arrangement McAdam and Buwert
attended Morton International, Dynachem Division, Warrington and spoke to Robert
Linsdell, who was asked to cause Steven Rawlings to submit DP/347(a) to similar
tests as had been carried out to PT/35(b). Linsdell examined DP/347(a) and DP/494
and asked that a further piece be cut from DP/347(a) so that the piece, DP/498, a resin
encased section, could be produced for photographic examination by microscope (the
HOLMES statements are not clear, but presumably what was meant was that Linsdell
asked for DP/498 to be cut from DP/347(a), after which it was encased in resin to
allow microscope photography). The statements record that 2 photographs (DP/499)
were produced by Philip Michael Walker from this and that the rest of the fragment
cut from DP/347(a), which the statements record was labelled DP/504, was retained.
[See below for discussion re DP/504, as the statements are not totally clear – it does
seem that Walker removed a cross-section from DP/347(a) and then only mounted
part of this, DP/498, the remainder later being designated DP/504. However, the
Crown appeared to proceed on the basis that it was John French of Ciba Geigy that
removed DP/504 from DP/347(a).] It is stated that Steven Rawlings took scrapings
from both sides of DP/347(a) and produced potassium bromide – “KBr Disks” (the
scraping from the non-track side was designated DP/496 (Crown label 408), the
scraping from the track side was DP/497 (Crown label 409)) – to facilitate infrared
spectrometry, and 2 spectra print-outs were obtained and compared to the spectra
print out for PT/35(b) (both spectra print-outs being designated DP/500, production
348) and statements were obtained from the three witnesses.

UPDATE: The Spectra DP/500






According to the police report Linsdell and Rawlings’ opinion was that the copper
tracks from DP/347(a) were 35 microns in height, which was similar to the height of
the copper tracks on the fragment. Rawlings concluded from the spectography of
material from both sides of DP/347(a) that all the absorbance peaks in the
“fingerprint” region of the spectrum of PT/35(b) could be matched to the major
absorbance peaks in the spectra for DP/347(a), so that they could be from the same
source, there being no evidence for them not being from the same source.

Linsdell’s manuscript statement (prod 361) bears out the above summary. In addition,
it records his description of DP/347(a) as being a single sided PCB, manufactured
from double-sided laminate material, screen printed with solder mask on the non-track
side, so that the solder mask was for aesthetic reasons and not to act as solder mask.
He states that surface mount technology board was somewhat more advanced in
design that what he envisaged when he saw PT/35(b), it was designed in an unusual
way, but by using surface mount technology the manufacturer reduced the size of the
timer considerably. Surface mount technology had been around for 10 years and in
production for 5 or 6 years. In 1985/6 the technology was not very common, perhaps
5-10% of production, whereas in 1992 it was 50%. The technology had the advantage
of small size, bulk and weight. Linsdell stated that having seen DP/347(a) he now
understood the peculiarities in comparison to the origin sample, as he had suspected
that PT/35(b) was somewhat unusual when he first examined it, and this had been
borne out.

In his CP Linsdell could not at first recall any visit by police officers subsequent to
the first visit in 1990. He was shown DP/347(a) and vaguely recalled having seen it
previously. He confirmed his signature was on the label, but could not recall when or
whether any tests were carried out on this sample. He was shown DP/496 and
DP/497, the scrapings taken from DP/347(a), but had no recollection of them. His
signature was not on the labels for them, although he saw Steven Rawlings’ signature
on the labels. He presumed Rawlings had done the scrapings but did not remember
this. He was shown DP/500, the spectrum printout, but his signature was not on this
label and he had no recollection of having seen it before. He examined the printouts
and said he did not think it possible to say that DP/347(a) and PT/35(b) were the
same. He was prepared to say that there was nothing in the printouts to suggest they
were not the same, but this was as high as he could take it. He was shown DP/498,
the resin encased section from DP/347(a) and vaguely recalled that it was removed by
his colleague Philip Walker. He thought it would have been examined
microscopically but he could not recall this being done. A PF’s note states that
Linsdell was confident but that his role was overstated in the police statements and he
was more a supervisory role, Rawlings having done the work.

In his DP Linsdell did recall the visit of police in 1992 and recalled being shown a
complete circuit board similar to the fragment he had previously been shown. He
knew comparative analytical tests were done on solder mask samples taken from the
complete board, using the same procedures as had been done for the fragment. He
said that from his own observations, he noted certain similarities. He referred to the
two samples having the same curve and routing and similar circuit design, which was
a “design feature”. This uniformity strengthened his belief that both boards had been
produced using the same means of production in a purpose made facility. He thought
it would be “a coincidence of some magnitude” if individual designers were to
produce the same characteristics in isolation, so he was of the belief that the fragment
could very much have been part of a board very similar to the one shown on the
second visit.

Linsdell did not give evidence.

Rawlings’ manuscript statement (prod 360) reflects the summary above, in particular
that in comparing the absorbance peaks for the samples from DP/347(a) and PT/35(b)
in the spectra printout (DP/500), it indicated that the two could have been from the
same source and there was no evidence for them not being- from the same source.

In his CP Rawlings confirmed that on 2/3/92 the police visited again and that he took
the scrapings (DP/496 and 497) from both sides of DP/347(a) and produced spectra.
He stated that only one side, the non-track side, had solder mask on it. He concluded
that the solder masks could be of the same type. There were slight differences in
some of the ratios but these were not significant, there was nothing to suggest they
were not from the same production run. The differences could have been because the
tests were done at different times and also because the original fragment was charred
and very small, thus restricting the sample size it was possible to obtain. He did state
that in court he would not be able to state absolutely that the solder mask on PT/35(b)
was no acrylete based, it being theoretically possible that, in the event the fragment
was exposed to high temperatures, the acrylete could have decomposed leaving the
other materials that would suggest epoxy based coating, as acryletes burn off at much
lower temperature than other parts of solder mask. He stated that this was only a
theory and he had not conducted any tests on it.

In his DP Rawlings recalled the 1992 visit and referred to his notes of it. He did not
add anythmg of note to what is stated above, other than that he took scrapings from
both sides of the board even although it was only solder masked on one side, as it
allowed him a control sample to show the presence of solder mask against.

Rawlings gave evidence but not in relation to the 1992 enquiries.

Walker’s manuscript statement (prod 362) states that he was asked by Linsdell to
prepare a micro section from DP/347(a), which he cut at a point indicated by DS
McAdam. He said he mounted a piece of this cross section into a mounting
compound, which was subsequently polished so that it could be viewed through a
microscope. This was DP/498. Microscopic examination revealed the copper track
“height” to be approximately 35 microns, which is one once weight, very commonly
used in the PCB industry. He produced 2 photographs (DP/499).

The terms of Walker’s police statement would suggest that he cut a cross section from
DP/347(a) and then mounted a piece of this cross-section, i.e. not the whole part that
he removed, into the compound. This would suggest that part of the cross-section that
was cut by Walker was not mounted. This would be consistent with the terms of
McAdam and Buwert’s HOLMES statements, that the mounted part was labelled
DP/498 and the remainder of the cross-section cut from DP/347(a) was labelled
DP/504. However, the statements and precognitions of Linsdell, Rawlings and
Walker do not mention DP/504. It is first mentioned in French’s HOLMES statement
(see 4 March 1992, below) which records that he was told by police that DP/504 had
previously been removed from DP/347(a). This would seem consistent with DP/504
having been removed by Walker. However, the CP of French suggests that the Crown
believed it was he who had removed DP/504, and then had removed DP/505 from
DP/504 (see below). The statements are not completely clear, but they do tend to
suggest that it was Walker and not French who cut DP/504 from DP/347(a). Buwert’s
CP does not mention DP/504 at all.

In his CP Walker stated that he had no recollection of the police attending in 1992
with DP/347(a), and had no recollection of removing a cross section fkom this board.
He confirmed that the label for DP/347(a) bore his signature, as did the label for
DP/498. He stated that the sample had been mounted in compound then polished so it
could be viewed through an optical microscope, and he confirmed that this is the type
of work he would have canied out. He confirmed that the label for DP/499 bore his
signature and that they were attempting to demonstrate the “height” of the copper
tracks on the cross section of the board. He stated that he came to the conclusion that
the height of the sample was approximately 35 microns, which is 1 ounce weight, and
that this was very common in the PCB industry. He said he could not provide the
Scottish investigators with any more information.

In his DP Walker stated that he understood the police revisited on 2 March 1992 but
he could not himself remember the date and that he may have spoken to the officers
on this occasion but to the best of his memory he did not conduct any further tests or
examination on the fragment or any other piece of material.

Walker did not give evidence.

Comparison between control sample and fragment: the height of the copper tracks in
both samples was the same, and the make-up of the solder mask did not appear
different. Linsdell himself made comments about how he felt the two came from a
common source.

NB The signatures of Walker, Linsdell and Rawlings are visible on the label for

This entry was posted in Chronology, DP/347(a), MST13, PT/35(b). Bookmark the permalink.

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