A man has gone on trial at the Central Criminal Court charged with murdering his baby son almost five years ago.

John Tighe, 40, of Lavallyroe, Ballyhaunis, Co Mayo, has pleaded not guilty to the murder of six-month-old Joshua Sussbier Tighe on 1 June 2013.

The prosecution said Mr Tighe killed his son by putting a wad of tissue into his throat.

They said it came the day after the baby's mother posted on Facebook that she was in a new relationship.

The court heard Mr Tighe maintains the baby grabbed a wipe or tissue while he had his back turned on him for a second.

Senior Counsel Paul Murray opened the case to the jury of four women and eight men.

He said Joshua was born on 16 November 2012, but the relationship between Mr Tighe and Joshua's mother, Natasha Sussbier, ran into difficulties and by June 2013 they were no longer living together and shared custody of Joshua.

Mr Murray said Ms Sussbier formed a new relationship and posted this on Facebook on 31 May 2013.

On the same day, Mr Tighe collected Joshua and brought him back to his house.

Just before 1pm, the following day, the jury was told a call was received by WestDoc Medical Practice from Mr Tighe.

He told the first person he spoke to that he was changing Joshua's nappy, that he went to the toilet for a second and he thought the child was "after choking on a baby wipe".

He said his son had gone a bit blue. The court heard Mr Tighe said it was "half way up his throat".

The prosecution told the jurors the doctor who arrived on the scene will give evidence that Joshua had passed away when he arrived.

The doctor could not see the wad of tissue when he looked in the baby's mouth, but could feel it when he put his finger into his throat.

The jury was told the object in the baby's throat was an "egg-shaped" wad or bolus made up of two pieces of tissue - 5cm in height and 3.5cm wide at its widest.

Mr Murray says the prosecution alleges this object caused the death of Joshua by obstructing his airway.

He said a six-month-old baby would be capable of crudely grabbing a piece of tissue and partially putting it in his throat.

But he said a baby of that age would not be capable of making the tissue into an object like this with his hands, would not be able to chew it to form an object of this size and would not have the capacity to swallow it to the extent that it could not be seen in his mouth.

He said the jurors would also hear other medical evidence.

Mr Murray said if the baby could not do this, the only other person in the house at the time was Mr Tighe.

He said Mr Tighe had always maintained this was a pure accident, that the baby was choking when he came back from the toilet and that he must have ingested a baby wipe.

He said the prosecution case was that this explanation did not add up.

Mr Murray said the jurors would have three questions to answer: Was the cause of death the obstruction of the baby's airway by the tissue?; how did the object get there?; what are the natural and probable consequences of an object of this size ending up in the throat of a six-month-old baby.

The court also heard from the man with whom Ms Sussbiar had formed a relationship.

Daniel Sommerville said he met Ms Sussbier in March 2013.  He agreed that he and Natasha had put a status update on Facebook on 31 May to say they were in a relationship.

Under cross-examination he said he could not say if Mr Tighe was aware of the relationship before then.

He also agreed that Mr Tighe had dropped over a puppy as a gift some time in the week before 31 May.

The jury also heard a tape of two phonecalls between Mr Tighe and West Doc Medical Practice - the out of hours GP service for the west of Ireland - on the afternoon of Saturday 1 June.

The calls lasted more than 23 minutes in total. 

Mr Tighe described how Joshua must have grabbed a baby wipe and was choking. He told the person on the phone that the baby had gone a bit blue and had some blood coming out of his mouth.

The jury heard nurse Liz Watson tell Mr Tighe to keep the baby's head down and to keep tapping the baby on his back and his front to try to dislodge the object in his throat.

In the calls, Mr Tighe told the nurse Joshua was breathing but not well, and noises from the baby can be heard in the background.

Towards the end of the tape, Mr Tighe told the nurse Joshua was not breathing and can be heard getting very distressed as he begged his son to breathe.

Mr Tighe became extremely distressed in court, as the tape was played.

Under cross-examination, from defence counsel Mícheál O'Higgins, Ms Watson agreed that she had told Mr Tighe to "tap" the baby's back instead of telling him to administer five sharp blows to the baby's back as laid down in the protocol for such emergencies. 

She agreed she possibly should have used the word "blow" instead of "tap".

Mr O'Higgins brought Ms Watson through the protocol. She agreed she had not told Mr Tighe to give five blows. She said she had encouraged Mr Tighe to put his fingers in to try to take the object out as she said he had said he could see it. 

She agreed the protocol said repeated sweeps with the finger should not be carried out as it could force the object further into the throat.

Ms Watson agreed that at one stage the situation seemed to be recoverable as Joshua was still breathing.  She said the protocol to give five sharp back blows to the baby was not given to Mr Tighe.

The trial is expected to continue until the end of next week.