Mobile phone analysis puts Joe O'Reilly's phone near the family home on the morning of the killing and this is not in keeping with his own account of his movement, an expert witness has told the jury.
It was the 11th day of the trial of Mr O'Reilly (35), Lambay View, Baldarragh, The Naul, Co Dublin, who has pleaded not guilty to murdering Rachel O'Reilly (30), his wife and mother of their two children at the family home on October 4th, 2004.
Oliver Farrell of engineering consultancy group Vilicom explained to prosecuting counsel Dominic McGinn how mobile phone networks worked.
He said the network was built up through a series of telephone masts (base stations), each carrying a number of transmitters which were generally pointed by antennas in three different directions.
The three different directions ensured there was "surround coverage". He said after a call or message was made, a signal would be sent out and the closest transmitter on the closest mobile phone mast, would pick it up.
The network would then page other transmitters while looking for the phone, he said.
Because transmitters had a limited capacity, there were more of them covering smaller arcs of coverage in urban areas. Mr Farrell said smaller areas of coverage were achieved by tilting the transmitters in a downwards direction, as you could a spotlight.
This meant there were fewer transmitters in rural than in urban areas and that arcs of coverage were equally bigger.
He said mobile phone sites must overlap, otherwise there would be coverage blackspots.
Mr Farrell then traced communications made by Mr O'Reilly's phone the day of the murder.
05.25.05 . . . Picked up by Balheary mast just north of Swords on the M1. The transmitter points north to northeast.
05.34.56 . . . Picked up by mast at Finglas ESB between M50 and M1, transmitter points north of Finglas
05.45.14 . . . Picked up by mast at Finglas Garda station, transmitter points in and around Finglas village. Asked by Mr McGinn whether that analysis corresponds to Mr O'Reilly's account of going from the house in Baldarragh to the Jackie Skelly gym, Mr Farrell said it did.
07.35.16 . . . Picked up by Nangor Road at Riverview Business Park just to the left of Bluebell, transmitter points north to northeast. Mr Farrell said this data corresponded with Mr O'Reilly's account that he was at the gym.
08.12.57 . . . Picked up by mast at Pat O'Donnell's, Chapelizod, by the M4. He said this accorded with Mr O'Reilly's account that he was at work in Bluebell Industrial estate at this time.
He then analysed data from nine calls.
08.46.47 . . . Picked up by mast at Airways between the junction of the M50 and M1 in Santry. Transmitter covers west of the junction.
08.48.14 . . . Picked up by mast at Willsborough on the other side of the M1, transmitter covers north of mast including the M1.
08.48.27. . . Picked up by same mast.
08.56.31 . . . Picked up past Richardstown, left of the M1. Transmitter covers centred on M1. Asked by Mr McGinn if this would also cover the R122 road, he said it would.
09.25.07 . . . Picked up by Murphy's Quarry mast. Mr Farrell described this mast as being "just down the road from the O'Reilly household". Transmitter points north-northeast
09.52.28 . . . Picked up by Murphy's Quarry, the same transmitter in the same mast again.
10.04.13 . . . Picked up by Richardstown mast, transmitter points north.
10.07.30 . . . Picked up by different transmitter in the same Richardstown mast, transmitter points south of Richardstown.
10.08.59 . . . Picked up by Balheary mast, south of Richardstown area but north of Balheary.
Asked if Mr O'Reilly's account that he travelled from his work in Bluebell Industrial Estate and went to the Broadstone Phibsboro bus garage corresponded with analysis of his phone for the same time frame, Mr Farrell said: "It does not correspond."
He added: "They indeed give a different picture," in that they showed a journey going towards north Co Dublin from Bluebell and then returning south from the same area.
10.38.27 . . . Picked up by North Circular Road phone mast right of Phoenix Park beside Park House, transmitter points south-southeast.
11.05.17. . . Picked up by Dominick Street mast right of last mast, east of NCR transmitter, points north-northwest back towards Park House.
Asked if this was consistent with Mr O'Reilly's account that he was in the Broadstone Phibsboro garage at this time, he said: "They are consistent with the description."
11.32.57 . . . Picked up by Pat O'Donnell mast in Chapelizod, transmitter points south-southeast.
Mr Farrell said this was consistent with Mr O'Reilly's account, although he noted it was not similar to one of his accounts, which stated that he did not leave the garage until 11.30 that morning. He said it would have been impossible for him to reach this mast so soon and that he must have left earlier.
12.01.17, 12.06.01 and 12.59.59 . . . all picked up by Killeen Road ESB mast which would accord with Mr O'Reilly's account that he was in work in Bluebell.
13.14.30 and 13.20.34 . . . all picked up by mast beside his place of work Bluebell.
Then followed 17 calls between 13.21.41 and 14.43.24. Mr Farrell said the analysis of these calls was consistent with Mr O'Reilly's account that he travelled from work to his home at this time.