Mr. Kelly died following a stabbing incident in Grafton Street in the Rosemount area.
Before the court are brothers Gary Anderson (25) and Sean Anderson (23) both of Grafton Street in Derry and Michael Dunlop (21) of Fern Park in Derry.
The Anderson brothers are charged with the murder of Karol Kelly on March 4, 2018.
Dunlop is charged with the murder of Mr Kelly, grievous bodily harm with intent on him and doing an act with intent to pervert the course of justice on the same date.
After the jury was sworn in Judge Philip Babington told them the trial is expected to last between three to four weeks.
They were also informed that the trial itself would not be starting today (Tuesday) and would begin properly tomorrow.