Graham Dwyer has pleaded not guilty to the murder of childcare worker Elaine O'Hara in Dublin two-and-a-half years ago.
A jury has been sworn in at the Central Criminal Court for the trial of the 42-year-old architect of Kerrymount Close in Foxrock, south Dublin.
Ms O'Hara - who was 37 - had been missing for a year when her remains were found by a dog-walker in the Dublin Mountains last September.
Mr Justice Paul Carney has told the jury the case will be difficult for anyone who is "particularly squeamish".
In a dark suit and tie, Graham Dwyer stood in court and answered 'not guilty' to a charge of murdering Elaine O'Hara at Killakee, Rathfarnham in Dublin.
He is alleged to have killed the childcare worker on August 22, 2012.
Mr Justice Paul Carney then began to swear in a jury for the trial which is due to start tomorrow and will last six to eight weeks.
He advised the jury panel that they should not serve if they have any connections with the parties involved or with a website alt.com.
He told them that the deceased had attended St Edmundsbury Hospital, Lucan before her death and that she had lived at Belarmine Plaza, Stepaside.
He also listed some of her previous home and work addresses in the south of the county.
He also said that this case will be difficult for anyone who is particularly squeamish - one woman was excused from serving on that basis.
It took nearly half an hour to swear in a jury of seven men and five women.