A baby, whose father is on trial accused of his murder, had paper that matched two different tissue boxes in his throat when he died, a forensic scientist has told the Central Criminal Court.

John Tighe, 40, of Lavallyroe, Ballyhaunis, Co Mayo has pleaded not guilty to murdering his son Joshua Sussbier Tighe at his home on 1 June 2013.

Bridget Fleming of Forensic Science Ireland examined the "bolus" or "wad" of tissue that was taken from the six-month-old baby's throat during a post-mortem examination carried out by pathologist Dr Khalid Jaber.

She told prosecuting counsel Paul Murray SC that it consisted of two pieces of tissue paper, one three-ply and one two-ply, that were crumpled together.

Gardaí gathered tissue paper from various parts of the house where Joshua died and Ms Fleming compared those with the pieces taken from the baby's throat.

She found that the three-ply paper matched tissue from a box found in the main bedroom, while the other matched tissue found in a box in the sitting room.

She said she analysed the tissue for its dimensions, the number of layers and the number of folds in the tissue.

She added that the tissue was not from a baby wipe.

The prosecution alleges that Mr Tighe murdered his son by putting the wad of tissue in his throat, causing death by asphyxiation.

Mr Tighe denies the charge and when speaking to emergency services said that he was changing the baby's nappy, went to the toilet and when he returned he was choking and had gone blue.

John Hoade of Forensic Science Ireland told Mr Murray that he took blood samples from Mr Tighe's pyjama bottoms and compared them to blood taken from Joshua during the post-mortem.

He said the DNA on the pyjamas matched that of the baby.

Further profiles taken from a baby grow and a baby vest also matched Joshua's blood, as did samples taken from stains found on the floor of the sitting room and a wall.

The baby grow and vest had multiple light blood stains on them.

Mr Hoade agreed with defence counsel Mícheál P O'Higgins SC that, if the baby was bleeding as Mr Tighe held him while trying to help him, that would explain the presence of Joshua's blood on his pyjamas.

Counsel pointed out that Mr Tighe, during a phone call to emergency services, said there was blood coming from Joshua's mouth.

Daniel Sommerville told Mr Murray that he met Joshua's mother, Natasha Sussbier, on St Patrick's Day 2013, shortly after she had separated from Mr Tighe.

Mr Sommerville and Natasha started a relationship around the start of May and she moved in with him.

On 31 May, they put a post on Facebook saying: "Daniel Sommerville and Natasha Sussbier are in a relationship."

Mr Tighe collected Joshua from Natasha later that day and the following day he died.

Under cross-examination, the witness agreed that it could have been "blindingly obvious" to the accused man that Natasha was in a relationship before the Facebook post.

He said he did not remember Mr Tighe seeing them holding hands, but agreed it is possible that he did.

Mr Justice Patrick McCarthy told the jury of three men and nine women to return to court on Monday as he and counsel must deal with a legal issue in their absence.