Denise Brown was a fun-loving 21-year-old woman who worked as a part-time computer operator. Like many of her friends she loved dancing and nightclubs, and she lived with her boyfriend and another couple in Nedlands. Denise is described by people as having been warm, friendly, trusting and naive.
On Wednesday 5 November Denise had spent the day with a girlfriend at the Coolbellup Hotel. She was waiting for a bus outside the Stoned Crow Wine House in Fremantle that evening when the Birnies pulled up alongside her and offered her a ride home.
It may have been her happy, trusting nature that led her to accept the ride from the Birnies instead of waiting for a bus. In any case, as soon as she was in the car a knife was held to her throat. She was abducted and taken to the Moorhouse residence where, like the women before her, she was raped, time and time again.
Cruelly, the Birnies forced her to make phone calls to tell friends she was okay. It was their way of throwing investigators off any trail, to slow down the inevitability that Denise Brown would be the fourth Perth woman reported missing in the space of 27 days.
The day after abducting Denise Brown from the street, the Birnies decided to kill her. They drugged her, and dragged the bound woman into their car. In a departure from their routine of heading to Gleneagle Forest, the Birnies headed north, and drove more than 60 kilometres to Gnangara Pine Plantation at Wanneroo.
Once they had arrived in the forest David Birnie decided he would rape Denise Brown again while he waited for darkness to fall. During one of the rapes he stabbed her in the neck with a knife, an injury which, while horrific, proved not to be fatal. Catherine Birnie found a bigger knife and handed it to her partner. He stabbed the badly wounded young woman again, this time believing he had killed her.
He set about digging a shallow grave and after he placed Denise Brown's body in it, he was shocked when she sat up, trying to escape. At this point David Birnie grabbed an axe and struck Denise Brown twice on the skull with great force. Then the Birnies covered her body with sand.