Oscar Pistorius reaches out to his uncle Arnold Pistorius and other family members as he is led out of court in Pretoria, South Africa, after being sentenced to five years in prison on Tuesday, October 21. Pistorius, the first double-amputee runner to compete in the Olympics, was sentenced for culpable homicide in the February 2013 death of his girlfriend, Reeva Steenkamp.
Pretoria, South Africa (CNN) -- Opening a third week of testimony, a gun dealer said South African Olympic athlete Oscar Pistorius had to know gun safety laws before purchasing his firearms and getting his gun licenses.
Sean Patrick Rens, who sold guns to Pistorius, said the athlete correctly answered a questionnaire.
Rens said Pistorius knew that it's not legal to shoot at unknown person seen breaking into your house, not legal to shoot at them if burglar bars separate you, but it is legal to shoot at them if there's no protection and they approach you with a weapon.
For it to be legal to fire, Rens said, "the attack must be against you, must be against a person, must be unlawful."
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Oscar Pistorius reaches out to his uncle Arnold Pistorius and other family members as he is led out of court in Pretoria, South Africa, after being sentenced to five years in prison on Tuesday, October 21. Pistorius, the first double-amputee runner to compete in the Olympics, was sentenced for culpable homicide in the February 2013 death of his girlfriend, Reeva Steenkamp.
Photos: Oscar Pistorius trial
These points are important, because the Pistorius defense team must show that not only did he made a mistake but that the mistake was reasonable in order for him to be cleared of killing his girlfriend, Reeva Steenkamp.
Prosecutors and the defense are jockeying over whether Pistorius intentionally murdered Steenkamp, or killed her in a terrible but understandable accident.
There's no question that he shot her through a bathroom door in his house early on Valentine's Day last year, hitting her with three hollow-tipped bullets, one of which probably killed her almost instantly.
But for two weeks in court, his defense team has chipped away at every witness who casts doubt on his story that he thought Steenkamp was a burglar and mistakenly acted in what he believed was self-defense.
Prosecutor Gerrie Nel has put up witnesses ranging from the pathologist who performed the autopsy, to ex-girlfriend Samantha Taylor, who said Pistorius kept a gun by his bed and went to investigate a sound in the night, weapon in hand, at least once while she was dating him.
The senior police officer on the scene the night of the killing testified Friday, but it's not clear he did much for the prosecution case.
The police investigation sounded in court like a catalog of bumbling, bad judgment, poor memory and petty theft.
Former police Col. G.S. van Rensburg described how he found a police ballistics expert handling Pistorius' gun without wearing gloves and reprimanded the officer, who apologized and put a pair on.
And he said he was "furious" when at least one of the Olympic athlete's valuable wristwatches disappeared from his bedroom as police investigated the crime scene.
He "body searched" his fellow officers, their bags and their vehicles but was unable to find the watch, which was worth several thousand dollars.
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He also said he had ordered the bathroom door through which Pistorius shot Steenkamp removed from the house, placed in a body bag and taken to his office, explaining, "The door is the most valuable evidence because the deceased was behind the door."
Earlier in the week, the defense attacked police handling of the door, implying that the evidence was unreliable because it was contaminated.
Van Rensburg resigned from the force in December after three decades, under fire for his handling of the door. Asked what he now did for a living, he choked up and said, "I am now coaching sports, and sports is my life."
Gory details lend Pistorius trial a 'CSI' flavor
Golden boy turned defendant
He's the 13th witness to testify for the prosecution in the murder trial of Pistorius, once South Africa's golden boy for the stellar track success that made him the first double amputee runner to compete in the Olympics.
Pistorius, 27, has pleaded not guilty to murder and three other weapons charges. Steenkamp, a model, was 29 when she was killed.
On Friday, Pistorius' lawyer Barry Roux ripped into van Rensburg's chronology of events on the night of the killing, presenting witness statements from three police officers whose accounts differed from van Rensburg's.
The former officer was so startled by the statement of police Sgt. Ntome Sebetha that he stared at Roux and said, "Amazing."
Later, Roux rattled van Rensburg so severely, pointing out clear differences between two pictures that the former officer said were the same, that van Rensburg refused to answer a question about how many keys were in another photograph.
"It's not a trick question," Roux said. "There's one key there."
Gruesome images
The former police colonel first took the stand Thursday and said paramedics were there when he arrived at Pistorius' address about 3:55 a.m., but Steenkamp was dead.
As he testified, the prosecution showed more than 100 police photographs taken at Pistorius' house after the killing, including the sprinter's 9 mm handgun, still cocked and ready to fire, on a bloody towel or bathmat on a blood-spattered floor.
On Friday, the court was shown a photo of a toilet covered in blood, but only van Rensburg saw photos of Steenkamp's body and closeups of her injuries.
Those gruesome pictures were not displayed on courtroom monitors.
Even so, Pistorius kept his head down, shielding his eyes with one hand, while prosecutor Nel talked the former police officer quickly through the sheaf of photos on the witness stand.
Pistorius vomited several times last week as pathologist Gert Saayman described Steenkamp's fatal wounds, and again when pictures of the injuries were accidentally displayed on monitors in court.
Gun at his bedside
The case against Pistorius is largely circumstantial, Nel said in his opening statement last week. Pistorius and Steenkamp were the only people in his house when he killed her.
Nel has been building a picture of what happened through the testimony of experts, neighbors who heard screaming and bangs that night, current and former friends of Pistorius' and a security guard who sped to the scene because of reports of gunshots.
Many prosecution witnesses' accounts are consistent with Pistorius' version of events: that he got up in the night, went out to his balcony to get a fan, came back inside and heard noises in the bathroom that he thought came from an intruder.
He said he took the gun and fired while calling for Steenkamp to call police. When she didn't answer, he realized she could have been the person in the bathroom, he said.
Neighbors said they heard a woman screaming before the shots were fired. But the defense is proposing that what neighbors thought was Steenkamp screaming in fear for her life was in fact Pistorius when he realized what he had done.
And the defense says that the sounds neighbors heard were not the gunshots, but the cricket bat hitting the door as he tried to rescue her.
Pistorius and at least two neighbors made phone calls to security after the shooting, allowing the defense to use phone records to establish a timeline of events.
Judge Thokozile Masipa will decide the verdict. South Africa does not have jury trials.
In South Africa, premeditated murder carries a mandatory life sentence with a minimum of 25 years. Pistorius also could get five years for each gun indictment and 15 years for a firearms charge he also faces.
If he isn't convicted of premeditated murder, the sprinter could face a lesser charge of culpable homicide, a crime based on negligence. The sentence for culpable homicide is at the judge's discretion. The trial looks set to go on for several more weeks.
READ: Gory details lend Oscar Pistorius trial a 'CSI' flavor
READ: Oscar Pistorius trial: Four unanswered questions, and an answered one
READ: Ex-girlfriend: Pistorius cheated on me, kept gun by his bed
READ: Gruesome shooting scene photos sicken Oscar Pistorius at murder trial
CNN's Ed Payne contributed to this report
Pistorius leaves the high court in Pretoria on Monday, October 13. A judge cleared Pistorius of premeditated murder last month, but he was found guilty of culpable homicide -- the South African term for unintentionally, but unlawfully, killing a person.
Pistorius speaks with his uncle Arnold Pistorius during his trial at the Pretoria High Court on Friday, September 12.
Pistorius cries on the stand in Pretoria on Thursday, September 11, as the judge reads notes while delivering her verdict.
Pistorius arrives at court on September 11.
Pistorius speaks to someone in court as his murder trial resumes in Pretoria on Thursday, August 7.
Pistorius sits in court in Pretoria on Tuesday, July 8.
Pistorius arrives at court in Pretoria on Monday, July 7.
Pistorius yawns during day 37 of his murder trial on June 3.
Pistorius hugs a supporter Wednesday, July 2.
Pistorius listens to evidence being presented in court on Monday, June 30.
Pistorius leaves the court in Pretoria on Tuesday, May 20.
Pistorius reads notes during his trial on Monday, May 12.
Ballistics expert Tom "Wollie" Wolmarans testifies for the defense on May 12.
A red laser dot points at bullet holes in the bathroom door for a forensic demonstration during the trial on May 12. Pistorius admits firing four bullets through the closed door, killing Steenkamp, but says he thought he was protecting himself from a burglar.
Pistorius returns to court as his murder trial resumes Monday, May 5, after a break of more than two weeks.
Pistorius gets a hug from a woman as he leaves court in Pretoria on Wednesday, April 16.
Pistorius rubs his eye Tuesday, April 15, after testifying during his murder trial.
Pistorius arrives at the court in Pretoria on Monday, April 14.
Pistorius' sister, Aimee, cries in court as she listens to her brother's testimony on Tuesday, April 8.
June Steenkamp, Reeva Steenkamp's mother, reacts as she listens to Pistorius' testimony on April 8.
Pistorius is hugged by his aunt Lois Pistorius in court on Monday, April 7.
Pistorius sits inside the courtroom as members of his defense team talk in the foreground Friday, March 28.
Pistorius leaves court on March 28. The trial was delayed until April 7 because one of the legal experts who will assist the judge in reaching a verdict was sick.
Steenkamp's mother, right, and family friend Jenny Strydom react in court Tuesday, March 25, during cross-questioning.
Cell phone analyst Francois Moller testifies during the trial on March 25. Questioned by the prosecution, Moller listed in order the calls made and received by Pistorius after he shot Steenkamp.
Pistorius cries as he sits in the dock during his trial on Monday, March 24.
Pistorius talks to defense attorney Barry Roux on March 24.
Pistorius holds his head while members of his family talk behind him on Tuesday, March 18.
Steenkamp's mother, wearing the white collared shirt, looks on while a police officer takes notes in court March 18.
Pistorius is hugged by his aunt Lois on March 18.
Pistorius takes notes Monday, March 17, as his murder trial enters its third week.
Pistorius covers his head as he listens to forensic evidence Thursday, March 13.
Forensic investigator Johannes Vermeulen, left, is questioned during the trial March 13.
Pistorius listens to questions during his trial on Wednesday, March 12.
A police officer takes part in a court reconstruction March 12. A police forensic expert said Pistorius was on the stumps of his amputated legs when he knocked down a locked toilet door with a cricket bat to reach his shot girlfriend. That counters the track star's assertion he was wearing his prosthetic legs at the time. Defense attorney Barry Roux countered by suggesting that even with his prosthetic legs on, Pistorius would not be swinging a bat at the same height as an able-bodied person.
Pistorius listens to cross-questioning on Monday, March 10.
Friends of Steenkamp's family watch Pistorius during his trial on March 7.
Pistorius covers his ears on Thursday, March 6, as a witness speaks about the morning Steenkamp was killed.
Pistorius' sister, Aimee, right, speaks with members of Steenkamp's family on March 6.
Pistorius sits in court on the third day of his trial Wednesday, March 5.
Pistorius appears on the second day of his trial Tuesday, March 4.
Members of the media work during a break in proceedings March 4.
Pistorius talks with Roux inside the court on March 4.
Pistorius speaks with his legal representatives on March 4.
Pistorius is escorted out of the court Monday, March 3, after the first day of his murder trial.
People try to get a glimpse of Pistorius as he leaves the court building on March 3.
Pistorius is seen shortly after arriving for his trial on March 3.
Pistorius walks into the courtroom on March 3.
Pistorius takes a drink of water March 3 during his trial.
The case has captivated South Africa. Here, Lauren Wentzel watches the proceedings from her home outside Cape Town on March 3.
June Steenkamp arrives at the court building for the start of the trial.
Pistorius' relatives wait inside the courtroom on March 3.
People at the court building wait for Pistorius' arrival on March 3.
