Barry Roux, for Pistorius, questioned Col Johannes Vermeulen about who reassembled the door when it was brought to the police’s ballistics section.
Roux quoted from Vermeulen’s testimony on Wednesday: “So when we put up the door there at the ballistics section on April 30  it was not necessary for me to go back to the [Pistorius] house.”
Roux said when Vermeulen gave his evidence he said “we put up the door”.
“But when confronted about the missing pieces you tried to move away from your presence at the assembly of the door,” Roux put to Vermeulen.
It emerged on Wednesday that when police reassembled the door Pistorius had smashed open with a cricket bat to get to a dying Steenkamp, some pieces were left out.
The door and the replica of the cubicle, complete with a toilet, cistern, and magazine rack, was set up next to the witness box in court GD. Four bullet holes are clustered on the right side of the door, just under the keyhole. The toilet is to the left of the door.
Vermeulen is the commander of the material analysis sub-section at the forensic science laboratory. He told the court he had more than 29 years of experience in scientific analysis and completed almost 1400 forensic investigations.
Pistorius is accused of the premeditated murder of model and law graduate Steenkamp in his home on February 14 last year. He is also charged with illegal possession of a firearm and ammunition, and two counts of discharging a firearm in public.
He allegedly fired a shot from a Glock pistol under a table at a Johannesburg restaurant in January 2013. On September 30, 2012 he allegedly shot through the open sunroof of a car with his 9mm pistol while driving with friends in Modderfontein.