The Central Criminal Court has been told that the body of nanny Aoife Phelan was found buried in a barrel under a pile of rubble in a hole in the grounds of a 25-year-old man's home in Co Laois.
Robert Corbet of Sheffield Cross, Timahoe Road in Co Laois admits killing Ms Phelan between 25 October and 7 November 2012, but he denies murdering her.
Ms Phelan was reported missing on 26 October 2012.
The court heard that she had told her parents three to four weeks previously that she was pregnant.
Retired Detective Sergeant Liam Mulhall told the court that he saw evidence of a fresh disturbance of the ground at Mr Corbet's home on 6 November 2012.
The next morning, gardaí began digging at the spot.
He said the digger uncovered a lot of heavy rubble and debris, including lorry parts and bricks.
He said the digger then discovered a blue barrel in the hole.
Sgt Mulhall said he inspected the barrel and saw a lady's shoe and jeans and what looked like black plastic further down the barrel.
He said he moved the jeans and saw a human leg and brought a halt to the investigation and preserved the scene.
He agreed it was a "very sad" discovery.
The court also heard that Ms Phelan's handbag and mobile phone were found in a vehicle belonging to Mr Corbet.
The court heard yesterday that Mr Corbet was arrested on 5 November and claimed Ms Phelan was pushy about wanting a relationship with him.
He told gardaí he snapped and repeatedly struck her before dumping her body.
He was re-arrested after Ms Phelan's body was found and he told gardaí he had brought Ms Phelan to a garage at his home and they had been arguing about the relationship.
He said he had caught her around her neck with his forearm until she was motionless, then he put a black sack around her head, tied it with cables and disposed of her body.
The jury heard the cause of Ms Phelan's death was asphyxia with blunt force trauma to the head and chest.
The trial is expected to last two weeks.