Pretoria, South Africa (CNN) -- Detailed forensic evidence at the Oscar Pistorius murder trial was interrupted twice Thursday by the accidental display of pictures of Reeva Steenkamp's dead body and mortal wounds, prompting the man who killed her to be violently ill.
Pistorius threw up after both defense and prosecution lawyers scrolled through evidence photos on monitors to find the ones they wanted to discuss -- flashing past the gruesome images as they did so.
There's a monitor directly in front of Pistorius as he sits in the dock, on trial for murder.
The South African Olympic sprinter admits that he killed Steenkamp, his girlfriend of about four months, on Valentine's Day last year, but says it was a terrible accident, not premeditated murder.
He shot her through a locked bathroom door in his house, saying he thought she was an intruder, then broke the door down with a cricket bat to get to her when he realized his mistake.
Pistorius, 27, pleaded not guilty to murder and three other weapons charges.
Aside from the stomach-turning photos of the victim shown for an instant, Thursday's evidence was dry and clinical, as two police officers involved in the investigation testified.
Forensic expert J.G. Vermeulen was up first, concluding his testimony about the door through which Pistorius shot Steenkamp, who was 29 when she died.
After Vermeulen, a police officer who was among the first on the scene described his arrival and Pistorius' house.
G.S. van Rensburg, who was police district commander on the night of the incident, said paramedics were already there when he arrived at Pistorius' address at about 3:55 a.m., but Steenkamp was dead.
Gun cocked and ready to fire
The prosecution talked van Rensburg through police photographs of the athlete's house taken on that night. They showed some small spots of blood on chairs in a downstairs sitting room, and a trail of blood that led upstairs.
Pistorius appeared calm and took notes as the photographs revealed a gun, still cocked, on a gray towel or bathmat in the bathroom. A black cell phone lies on the floor next to it and blood spatter can be seen on the floor.
Another image showed a bloodstained towel in the bathroom, as well as a cricket bat and bullet cartridge on the bathroom floor, next to large bloodstains.
The court also saw a photo of a key on the outside of the inner toilet room door. This is potentially consistent with Pistorius' story that he broke the door open in order to get the key and unlock it from the outside.
Another showed a fan by the right hand side of the bed, which may gel with Pistorius' account that he went out to get the fan from the balcony before hearing noises he thought were made by an intruder.
The photos also indicated that Pistorius kept an air rifle and baseball bat by the bedroom door.
Other police photos included one of a magazine with bullets and pouch taken from the right-hand bedside drawer, and a close-up of the magazine with a hollow-tip bullet.
Stumps or prosthetics?
Earlier in the day, the athlete looked tired as he watched his defense lawyer painstakingly cross-examine the police forensics expert, whose testimony a day earlier threatened to discredit him.
For a second day, attorney Barry Roux picked at Vermeulen's testimony with fastidiously detailed questions about the validity of evidence offered by the dents, gashes and scratches on the door.
On Wednesday, Vermeulen, a police colonel, provided some of the trial's most dramatic testimony by swinging Pistorius' own bat at that very door from Pistorius' home, assembled in court for the judge in the Pretoria courtroom to see.
The prosecution and defense disagree over whether the runner was wearing his prosthetic legs at the time he broke into the toilet.
The officer concluded that Pistorius was on the stumps of his legs when he battered the door.
Pistorius' legs are amputated below the knees, and he wears prostheses. He is widely known for the blade-shaped ones he dons for track competitions, which have earned him the nickname "Blade Runner."
As Roux grilled Vermeulen, images quickly flipped by, and a photo of Steenkamp's body lying on its back and other bloody scenes flashed on the monitors around the court. One is directly in front of the accused.
Pistorius' face sank into his hands.
That torment repeated itself later in the day. That's when Pistorius could take it no longer.
After he vomited, the prosecution had graphic photos removed from the slide presentation.
The runner also threw up last week in court, when experts discussed details from Steenkamp's autopsy.
Gun at his bedside
The case against Pistorius is largely circumstantial, prosecutor Gerrie 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 it could have been her in the bathroom, he said.
Samantha Taylor, a former girlfriend of Pistorius, testified Friday that he reacted similarly once when she was sleeping at his house.
She said he once heard something hit a bathroom window and woke her up to ask if she'd heard it, too, before taking his gun and going to investigate. Taylor said Pistorius woke her up other times when he thought he'd heard a noise.
Who was screaming?
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.
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 is expected to take at least three weeks.
CNN's Richard Allen Greene reported and wrote from Pretoria, Ben Brumfield wrote from Atlanta. Marie-Louise Gumuchian in London contributed to this report.