Cell Site Analysis
IN HER MAJESTY'S COURT OF APPEAL IN NORTHERN IRELAND
Neutral Citation no. [2008] NICA 5
THE QUEEN v RICHARD DAVID McCARTAN and BARRY DAVID SKINNER.
Appeal Court: Kerr LCJ, Campbell LJ and Morgan J
http://www.courtsni.gov.uk/NR/rdonlyres/4F39A7FC-5350-4E4B-BB76-FA8DC4BA08D6/0/j_j_KER7057Final.htmIt is not proven with cell site analysis that evidence obtained relating to mobile call records, the Masts and their details associated with handling the calls and conducting radio test surveys combined together form a precise indication of the geographical location of a mobile telephone at the material time. Therefore, it is unlikely an alleged opinion that it is consistent to place a mobile telephone at a particular location holds weight. That cell site analysis might generally indicate the possible movement of a mobile telephone in relation to Masts that it used and no more.
Whilst the Appeal Case for the appellants (McCartan and Skinner) did not succeed it was not because cell site analysis was able to pinpoint the location of the appellants' mobile telephones, which it is unable to do, but the appellants' failure to identity what was happening with their mobile telephones at the material times. The following commentary from this Appeal Case is worth reading.
'The cell site analysis
[37] An expert in this field, David Sanderson, gave evidence, submitted a report on the subject and made a Power Point presentation to the court. Mr Fee suggested that Mr Sanderson’s evidence established that (a) call mapping was carried out in respect of telephone 008 (attributed to Mr McCartan) and telephone 301 (attributed to Mr Skinner); (b) call mapping provides an approximate indication of where a mobile phone was when a call was made; (c) call mapping is used primarily to show the likely movement of a cellular phone with a general indication of location; (d) the cellular phone may be anywhere within the best serving coverage of the sector; (e) there is boundary overlap between sectors served by different masts; (f) the extent of the best serving coverage sector is unknown; (g) the indication of movement of the person using the telephone is no more than consistent with a suggested pattern of progress – it cannot establish positively that the user of the telephone in fact moved in the mooted direction; (h) calls 15, 16 and 17 from 008 at 20.53: 20.55: 20.55 were made when the telephone was not in the vicinity of Euston Street.
[38] On the basis of this evidence Mr Fee argued that the cell site analysis did no more than provide a very imprecise indication of general movements. In the absence of a capacity to identify a precise location of the telephone within the area of best coverage it was not possible to provide any precise indication of travel direction. We are disposed to accept that Mr Fee has correctly identified the limitations that apply to the cell site analysis. As he has acknowledged, however, it does provide a general indication of the movements of the users of the telephones. If the appellants followed a different pattern of movements on the day in question, it was open to them to give evidence about those movements and to explain where they had been at the critical time in relation to the shooting. Their failure to do so, combined with the general indication that the cell site analysis provided, constituted strong evidence against them that their movements were as indicated by that analysis. In Mr McCartan’s case, his inquiry of the interviewing police officers as to how precisely he could be tied down to a particular area was also, in our judgement, extremely telling.'
The comments of the Appeal Court in para [38] suggests the appellants' own lack of self-preservation to state what their mobile telephones were doing and the reasons for going in a direction following the line of Masts used for handling calls, undermined the cell site analysis element of their appeal.
