GOOD practice guidelines relating to the seizure of mobile phones in cases involving digital evidence were not followed by police investigating the deaths of Nathan Gault and Debbie Whyte, it has emerged.

Mobile phone expert, Thomas Marryat, told the inquest into their deaths that, according to guidelines from the Association of Chief Police Officers (ACPO), mobile phones seized by police in the course of an investigation should be isolated from their network at the earliest possible opportunity.

Mr. Marryat said that the simplest way to do this was by turning the phone off.

Speaking via videolink, he said that this was to prevent data from being deleted from the device either accidentally or deliberately.

The expert also explained that any further incoming data, such as calls or texts, could “overwrite” existing data, such as deleted calls or texts, potentially rendering this data untraceable.

In a report prepared by Mr. Marryat for the Coroner ahead of the second inquest, he concluded that the mobile phone seized from Yvonne Seaman, the driver of the car that hit the two teenagers, had not been isolated from the network at the time.

The inquest heard that, following the seizure, it was a further 60 days before it was examined by an officer from the PSNI’s E-Crime Unit.

Mr. Marryat stated that the failure to isolate the phone from its network was in contravention of the ACPO guidelines, which would have been in place in 2008.

The expert confirmed that, after the phone was seized, it received five incoming calls and a text message which had potentially overwritten previous data, rendering it “non-recoverable”.

Mr. Marryat told the inquest that one way to ensure that police had a “definite” list of calls and texts relating to the phone would be by obtaining connection records from the network provider.

He said that “best practice” would be to examine the connection records along with the handset.

The inquest heard that police had not obtained the connection records relating to Yvonne Seaman’s phone.

During cross-examination, Mr. Marryat said that, in the UK, service providers were only legally obliged to keep these records for 12 months.