The jury is out in the Graham Dwyer murder trial.

The architect of Kerrymount Close, Foxrock in Dublin denies killing childcare worker Elaine O'Hara at Killakee mountain in August 2012.

At 3:30pm the clock started on the jury's deliberations. They will resume their task tomorrow morning.

Mr Justice Tony Hunt spent most of the day giving them legal directions and a summary of the evidence.

Ms O'Hara was last seen alive at around 6pm in Shanganagh Park on August 22nd, 2012.

The judge said the last 40 or so days of evidence boils down to the jury's view of what happened in the three hours that followed.

He said suicide must be considered but one thing is certain - if two people went out that night, only one came home.

He told the jury they must ask themselves why did the other one not come home?

The prosecution alleges Mr Dwyer stabbed Ms O'Hara to death for sexual gratification.