Oscar Pistorius 'Broke Every Rule' Night He Shot Girlfriend, Expert Says

PRETORIA, South Africa March 18, 2014— -- The man who devised South Africa's gun safety test said today that Oscar Pistorius had "broken every rule" of gun safety the night he shot his girlfriend Reeva Steenkamp through a locked bathroom door.

Pistorius' murder trial was focused largely today on his lawyer criticizing the police investigation. Reviewing photos taken by police of the murder scene and the time stamps on the photos, defense lawyer Barry Roux repeatedly pointed out how key objects had been moved.

Pistorius, 27, is accused of murdering his girlfriend, but Pistorius claims that he mistook her during the night for an intruder.

Part of today's largely technical testimony included Capt. Christiaan Mangena who described how he used lasers to help determine the trajectories of the bullets through the bathroom door. He said three of the four rounds that pierced the door did not strike the other side of the bathroom because they were lodged in Steenkamp's body.

As he described Steenkamp's wounds, including her black vest that had a bullet hole in it, the victim's mother June Steenkamp glanced briefly at Pistorius, who dropped his head in his hands and sat hunched over until the court adjourned for the day.

ABC News obtained fresh documents today, including used targets from Pistorius' practice shooting showing a series of shots all close to the bullseye.

Earlier court testimony detailed the arsenal of guns that Pistorius had and his former teacher Sean Rens told the court that Pistorius had a “great love and enthusiasm for guns.”

Rens also testified that Pistorius was aware of gun safety and had passed a firearms safety test. He read from a written firearms test he administered to Pistorius, demonstrating that Pistorius understood when it may and may not be acceptable to discharge a firearm. One specific hypothetical question outlined a scenario in which one sees strange armed men in one’s home stealing a stereo. Only in the scenario where two armed man advance on him in his home, with no security gate between them, did Pistorius reply that he would fire his gun.

In the section on "the importance of target identification", Pistorius answered, "Know your target and what lies beyond it..

In an interview with ABC News today, Andre Pritorius, the man who wrote the exam that Pistorius and all South Africans take before getting licensed to own a gun, said that shooting Steenkamp through a bathroom door without knowing for certain who was on the other side violated that rule.

"That came as a big surprise to the general public because ... he got the answers correct when he took the test not too long ago, but unfortunately the night of the shooting he's broken every rule," Rens said.

Pistorius passed the written test just weeks before shooting Steenkamp.

The defendant's sister, Aimee Pistorius, was stopped by some members of the public today to offer support to the Pistorius family and assurances that he would be acquitted. Aimee Pistorius held their hands and thanked them for their prayers.

Pistorius, the paralympian known as Blade Runner, could get at least 25 years in prison if convicted her murder.

ABC News' Liezl Thom and Mollie Riegger contributed to this report