A sergeant with the Garda computer crime unit has told the trial of Graham Dwyer of a text message retrieved from Elaine O’Hara’s computer that included the remark “must get fit for the murder”.

The trial resumed at the Central Criminal Court on Wednesday morning following three days of legal argument in the absence of the jury.

Mr Dwyer (42), an architect from Kerrymount Close in Foxrock, is charged with murdering Ms O’Hara (36), from Stepaside, Co Dublin, on August 22nd, 2012. The prosecution has alleged he lured Ms O’Hara up the Dublin Mountains and killed her for his own sexual gratification. The father of three has pleaded not guilty.

Wednesday’s evidence focused mainly on data extracted from mobile phones and laptops purported to have belonged to both Mr Dwyer and Ms O’Hara.

Sgt Alan Browne agreed with the prosecuting barrister Anne Marie Lawlor that a computer “saves data in all manner of ways”.

He outlined to the court how text messages from an 083 number, which the prosecution alleges belongs to Mr Dwyer, were backed up on Ms O’Hara’s computer and retrieved by detectives using specialised software.

Several messages from the 083 number to Ms O’Hara’s phone were read to the court, including one which read: “Looking forward to getting a new bike tomorrow to try and lose weight. Must get fit for the murder.”

Another message from the 083 number read: “Terrible 15 per cent pay cut and came fifth in flying.”

The court then heard a message from Ms O’Hara’s phone, which read: “Sir welcome to reality.”

Another text from Ms O’Hara’s phone was shown to the jury on screen. It read: “Yes sir, dying for more play sir.”

Sgt Browne then explained to the court the process of extracting data and ascertaining dates and timestamps in relation to the messages.

A text from the 083 number on March 31st, 2011 read: “Yes, beautiful baby girl [name of child redacted]. Glad you enjoyed the other night, many more sessions like it to come. See you sometime over the weekend.”

Another text from Ms O’Hara’s phone, this time on November 15th, 2011 read: “Sir, any chance you get an 086 phone sim I get free texts?”

On the same date, the 083 number replied: “No problem. Away in Poland from tomorrow so see you Sunday.”

Earlier, a financial crimes analyst with expertise in the extraction of data from electronic devices told the trial that there were 14 files with hundreds of text messages “of interest” on mobile phones he examined.

The court heard the analyst holds expertise in the examining of electronic devices, advanced mobile phone analysis, and the extraction of data. He works for the Criminal Assets Bureau, and as such was entitled to anonymity.

The analyst said he utilised a data recovery tool that “examines a large block of data and tries to recover as much data as possible”.

He told the court he was asked by detectives investigating the disappearance of Elaine O’Hara to examine a number of devices including two mobile phones.

The analyst was successful in extracting text messages sent and received from the phones, he said.

Also giving evidence was Detective Garda Brid Wallace, who also holds expertise in the examination of software. She said she examined the hard drive of a computer and an iPhone belonging to Ms O’Hara.

Data was retrieved from what was referred to as an “unallocated cluster” in the iPhone, which Det Gda Wallace described as free space on the phone which may contain remnants of deleted files.

The court heard that if a person deletes a file, remnants can be found in these “unallocated” areas until they are overwritten by saved files. Files in these areas of the device cannot however be searched for, she said.

She added that text messages were discovered on Ms O’Hara’s iPhone from the 083 number, and that that number had been saved in the phone under the name ‘David’.

After doing a search of this number on the computer, a calendar entry was found marked “Graham’s phone number”.

Paul Healy, an employee of the 02 store on Grafton Street, Dublin, told the court that at approximately 4.30pm on November 30th, 2011, he sold two Nokia mobile phones to one individual.

He said that because it was a pre-pay deal, the customer was not required to provide any identification. “There were no details given, other than the phone number,” he said.

Ms O’Hara was last seen at about 5.45pm near Shanganagh Cemetery in Shankill, Co Dublin, on August 22nd, 2012.

Her remains were found in a forested area on Killakee Mountain, Rathfarnham, on September 13th, 2013, by a woman walking her dog.

The trial continues Thursday in front of Mr Justice Tony Hunt.