The Litvinenko Inquiry

Part 6 | Chapters 1 to 8 | The polonium trail – events in October and November 2006
6.12 Beyond that finding, the principal questions that arose were, first, the level of each of
the findings and, second, the inferences that could be drawn from the results.
6.13 In order to provide an evidential basis for assessing these questions, a schedule was
compiled containing all the results of all the testing that had been conducted at the
scenes that were relevant to the investigation. I admitted this document – which was
referred to during the course of the hearings as “the contamination schedule” into
evidence. 6 It is an extremely long document, running to over 260 pages. In common
with almost all the documents that I have admitted into evidence, the contamination
schedule is available on the Inquiry website. The schedule contains very much more
detail regarding the testing results than is included in this Report; those wishing to
analyse this part of the evidence in more depth will find it an invaluable tool.
6.14 A1 gave oral evidence twice: on Day 2 and Day 20. On the second occasion she was
asked to express an opinion as to inferences that could be drawn from each of the
readings, in particular those in the higher range. Broadly speaking, A1 divided the
readings into two categories.
6.15 A1 categorised a small number of the very highest readings as indicating a site
of primary contamination, a term that she defined for these purposes as, “the
contamination that has come from the main source of material”. In practical terms, A1
agreed that the term referred to the first point of contamination – for example, where
a solution containing polonium 210 had been directly applied to a surface. 7
6.16 The other category, referred to during the hearings as secondary or transferred
contamination, comprised sites where the contamination had been caused not as
a result of exposure to the main source of material – i.e. polonium 210 – but rather
as a result of the transfer of contamination, either directly or indirectly from a site of
primary contamination. A1 explained that there was: “a range of ways in which the
contamination from the original source can be transferred so that could potentially be
on somebody’s hand, by somebody’s foot, et cetera”. 8 She also stated that:
“… the transfer of polonium from primary contamination areas to other areas is
dependent upon the physical and chemical properties of polonium and the surface
of the materials on which it is deposited. The amount of contamination transferred
is dependent upon the amount of original activity present on each successive
surface to which it is transferred.” 9
6.17 One important feature of the forensic testing in this case was that it was conducted
some weeks after the dates on which the contamination appears to have taken place.
As will be seen from the contamination schedule, most of the testing was undertaken
during December 2006. On the assumption that the contamination occurred in late
October and early November 2006, in each case there was a gap of several weeks
between the date of contamination and the date of testing.
6.18 A1 explained that this delay caused the readings to be lower than they would have
been at the time of contamination. First, in each case the level of alpha radiation
being emitted will have decreased during the intervening period as a result of the
rapid radioactive decay that is characteristic of polonium. Second, in some cases
6
INQ017934
7
A1 2/149-150
8
A1 2/150
9
A1 2/149
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