The Litvinenko Inquiry

The Litvinenko Inquiry
environmental conditions such as the cleaning of surfaces or (in the case of sinks,
drains, etc) the effect of running water will have further reduced the readings, a point
to which I shall return.
6.19 Finally for the purpose of this introduction, it should be noted that different considerations
flow from positive and negative findings of contamination.
6.20 In the instances where contamination was detected in relation to a place or an object,
there is a positive finding that calls for explanation. The existence of that positive
finding is not affected by the fact that, for the reasons discussed above, the original
level of contamination is likely to have been higher than that found.
6.21 The position is somewhat different where a location was tested without any positive
findings of contamination being made. As we shall see, there were a number of these
‘negative findings’ during the course of the investigation. They included buses on which
Mr Lugovoy and Mr Kovtun travelled, and also other buses on which Mr Litvinenko
had travelled.
6.22 One explanation for such findings is that the person of interest was not contaminated
at the time that he travelled on the bus. This is the counterpart to the conclusion
drawn in the case of positive findings of contamination, i.e. that the person of interest
was contaminated at the relevant time.
6.23 In the case of negative findings, however, there are other possibilities. One is that
the person of interest was contaminated at the time, but that he did not contaminate
the bus, perhaps because the journey was too short, and/or he did not sit down or
touch anything. Another possibility is that the person of interest was contaminated at
the time of travel and did contaminate the bus, but the contamination was no longer
present at the time of testing, as a result of decay and/or environmental factors such
as cleaning.
6.24 I therefore consider that the negative findings must be approached with caution. Given
the different possible explanations for these test results, and without any means of
determining which is the accurate explanation in any particular case, these results
must generally be treated as being neutral. There is one possible exception to this
general approach, to which I shall return below.
112