Lundy's lawyer, David Hislop, today walked ESR forensic scientist Bjorn Sutherland through a possible scenario of how the 38-year-old mother and her 7-year-old daughter were killed.
A mark on the pillow next to Mrs Lundy could indicate the attacker may have missed his first hit with the weapon, which woke her, Mr Hislop said.
She then moved and attempted to defend herself from the blows coming from her assailant who was standing to the right of the bed in front of the bedroom's curtains, where there was a void of blood.
Mr Sutherland agreed it was a possible scenario, but went further to say the blood spatter indicated there could have been a second position for the attacker, that could have been on the bed.
After killing Mrs Lundy, the attacker would then have targeted Amber, who was standing in the bedroom doorway, but had turned to leave.
Mr Sutherland said she was brought down with a "forceful blow" to her head followed by further blows as she was near or on the floor.
"The implement was already stained with Christine Lundy's blood."
Orange and blue fragments of paint were found on the victims' bodies and embedded into the bones of their skulls, Mr Sutherland said.
The paint was a visual match to paint on the tools in Lundy's shed.
There were no fragments of paint found on Lundy's clothes or in his vehicle, he said.
Mr Sutherland agreed with Mr Hislop that the attacker's exposed clothing could not have avoided the blood that was being cast off the weapon.
Mr Hislop spent some time today asking Mr Sutherland about contamination at the scene, including when Mrs Lundy was transferred into a body bag and taken out of the house through the conservatory window.
Considering she had a "mutilated face, that's a pretty tricky process isn't it", he asked.
Mr Sutherland said great care had been taken and he was constantly monitoring his and his colleagues' protective clothing to ensure it stayed clean.
Earlier today Mr Sutherland said particles of blood that could have come from Amber Lundy were found on her father's polo shirt.
Two other marks that also tested positive for blood were also found on the shirt, he said.
The blood particles could have come to be on the top through contamination, Mr Hislop suggested.
Mr Sutherland rejected that. "There was a physical separation of items from the crime scene and the items from Mark Lundy."
Mr Hislop suggested Mr Sutherland would not know if contamination happened before the top came to be examined in the laboratory.
The trial in front of Justice Simon France and a jury of five women and seven men continues.
