In later testimony, a police ballistics expert described how he tried to reconstruct the angle of the gunfire, citing tests that suggest the bullets were fired about 2.2 metres (approximately 7ft) from a toilet door.
The bullets punctured the door and three of them hit Reeva Steenkamp, who was in the toilet cubicle.
Warrant officer Bennie van Staden, a police photographer, took hundreds of photographs of the scene, including of blood stains, bullet casings, a gun and a cricket bat found inside the bathroom in the hours after the shooting.
The double-amputee Olympic runner shot Ms Steenkamp, 29, at his home before dawn on 14 February last year.
Defence lawyer Barry Roux has challenged previous police witnesses in the Pretoria court room where the trial is being held, seeking to uncover contradictions and reported mishaps to support his argument that officers bungled the investigation.
That allegation was made by Pistorius at the start of the trial when he pleaded not guilty to murder over Ms Steenkamp’s death.
In a painstaking process, Mr Roux minutely examined many of the images taken by Mr van Staden and another police officer and pointed out that objects at the crime scene had been moved and were in different positions in photographs.
Mr Roux also used time-of-day records on the images to show that the two policemen taking photographs were in the same room at points, even though Mr van Staden testified he was working alone.
Pistorius, 27, is charged with premeditated murder for killing Ms Steenkamp. He denies murder, claiming he shot his girlfriend accidentally, thinking she was an intruder in a toilet cubicle in the bathroom.
He claims he struck the toilet door with a cricket bat to get to her after realising what he had done.
Prosecutors allege that Pistorius killed Ms Steenkamp after an argument.
Pistorius’s lawyer asked Mr van Staden to explain differences in photographs of the position of the 9mm pistol Pistorius used and of the cricket bat.
“It seems there was movement of the bat” in the interval between two photographs taken by Mr van Staden, Mr Roux said.
“It seems like that,” Mr van Staden conceded.
The police photographer also acknowledged that two photographs of the gun indicated that a mat underneath it could have been shifted.
Mr Roux said one photo also differed from the other because it showed a wooden splinter on the gun handle. Captain Christiaan Mangena, the police ballistics expert, said the bullets were fired at a slightly downward angle and entered the toilet door below the shoulder level of Pistorius, if he were standing without prosthetic limbs.
Pistorius said he was on his stumps when he fired. Prosecutors do not dispute the assertion, after initially alleging he was on his prosthetic limbs when he killed Ms Steenkamp.
Mr Mangena said he used thin rods and the beam from a laser mounted on a tripod to try to determine the trajectory of the bullets through the door.
He also described entry and exit wounds on Ms Steenkamp’s right arm and her head, and bruises on her chest where a “projectile” struck without penetrating.
The trial, which is being partially televised, continues before a judge.