Oscar Pistorius's defence team picked through the testimony of a police photographer who took images of the bloodied crime scene where the athlete shot dead his girlfriend.
The court was shown graphic photographs of a bloody cricket bat and bathroom floor and the 9mm pistol used to shoot Reeva Steenkamp.
Defence lawyer Barry Roux said police photographer Bennie van Staden caused a "great disturbance" by moving evidence and suggested police testimony contained suspicious timing inconsistencies.
Mr Van Staden said he always took pictures of an original crime scene, but that he moved bloodied towels and a duvet in order to check for more evidence.
Mr Roux argued that bungles by police had tainted the scene to such an extent that the evidence could not be used.
The defence insists these changes make it difficult to prove the sequence of events in the early morning hours of Valentine's Day last year.
"How does it happen there was such great disturbance in that scene?" Mr Roux asked about the pictures.
The lawyer also claimed data on the photos suggested a "great overlap" in when photographers documented the scene, contradicting testimony that they worked at different times.
"You were taking photos together in the bedroom and bathroom," Roux told Mr Van Staden, who had earlier testified that he was alone when he documented the bathroom where Ms Steenkamp was shot dead.
Mr Pistorius, 27, denies intentionally killing Ms Steenkamp, saying he shot the model through a locked toilet door thinking she was an intruder and then used a cricket bat to bash through to reach her.
His defence team has pointed out several police mistakes at the crime scene, including an officer handling the suspected murder weapon without gloves and another stealing a watch.
Mr Roux quizzed Mr Van Staden about the policeman who handled the murder weapon.
"I was informed that Colonel Motha handled the firearm and put it on 'safe'" said Van Staden.
"And what did you do about that?" asked Mr Roux.
"I spoke to him and reprimanded him," said the police photographer.
Following Mr Van Staden's testimony, prosecutor Gerrie Nel called police ballistics expert Captain Chris Mangena, a 20-year veteran of the force with 19 years in the ballistics division.
His testimony saw Mr Pistorius cry, tears running down his face, and cover his ears as lawyers tried to determine whether he was on his fake limbs when breaking the door down or still on his stumps, as prosecutors allege.
Cpt Mangena said he measured the height of the bullet holes in the door and calculated the angle of the shots.
"The angle that I can determine, which is between five and six degrees," he said.
"Downward," clarified Mr Nel, hoping the to suggest the athlete was on his prosthetic limbs.
"It's a downward angle," said Cpt Mangena.
The ballistics expert, who is still to give his conclusions, said he took measurements of Mr Pistorius with and without his prosthetic legs.
Cpt Mangena also described Ms Steenkamp's bullet wounds to her head, arm, hip and hand and bruising on her body.