In a statement read during a bail hearing Tuesday by his lawyer, Barry Roux, Pistorius, a paraplegic runner, gave his account of events Feb. 14, when his girlfriend, model Reeva Steenkamp died in his house in a gated community in Pretoria, The Guardian reported.
The hearing was adjourned until Wednesday after the defense team said it wanted the option of presenting more evidence once it gets information requested from the prosecution.
Pistorius, a double-amputee who races on carbon-fiber blades, said the two were asleep when he heard a noise as he was closing a sliding door on his balcony. He said he felt vulnerable, grabbed a gun and shot through the door. When he saw Steenkamp wasn't in bed, he used a cricket bat to open the door.
Steenkamp was alive, but died in his arms, Pistorius said in his statement.
"I fail to understand how I could be charged with murder, let alone premeditated murder, as I did not intend to kill my girlfriend Reeva Steenkamp," he said in the statement.
In presenting the prosecution's version of events, Prosecutor Gerrie Nel said there was an argument before the shooting. Later Pistorius got up from bed, attached his prosthetic legs, got a gun, walked about 20 feet to the bathroom and shot Steenkamp four times, hitting her three times.
"She could not go anywhere," Nel said. "It must have been horrific."
Pistorius, 26, sobbed as prosecutors offered their version of how Steenkamp died.
During his presentation Nel asked why a burglar would lock himself in the toilet. As a counter, Roux asked how the prosecution knew Pistorius attached his prosthetics and walked to the bathroom.
Magistrate Desmond Nair ruled that Pistorius should be charged with premeditated murder, an offense that makes it more difficult for a defendant to get bail. In his statement, Pistorius said he would not leave the country if granted bail and intended to stand trial. He said he would surrender his passport and not interfere with witnesses.
Nair said during the hearing he could reduce the charge once he had heard all the evidence.
Friends and family mourned Steenkamp, 29, at a funeral service in her hometown of Port Elizabeth.
"There's a space missing inside all the people she knew that can't be filled again," her brother, Adam Steenkamp, told reporters.
Reeva Steenkamp was a law school graduate with a rising modeling career. She was on the cover of FHM magazine and recently appeared on a reality TV show.
Authorities have released very little about a possible motive in the shooting.
Among the items recovered from Pistorius' home were Reeva Steenkamp's iPad, an overnight bag and a bloodied cricket bat.
Police spokeswoman Denise Beukes said authorities were alerted to the shooting by neighbors, and residents had "heard things earlier."
Police said there were "previous incidents" at Pistorius' home, including "allegations of a domestic nature," but did not provide details.
Pistorius' agent said Monday all future races the double amputee was contracted to compete in have been canceled.
Pistorius, who won two gold medals and a silver at the 2012 Paralympic Games in London, was the first paralympic sprinter to participate in the able-bodied Summer Olympics in London.
Several companies have withdrawn sponsorships.
"We have no plans for using him in any upcoming campaigns," Nike spokeswoman Mary Remuzzi told United Press International Monday.
The decision to drop Pistorius was made after he was charged in Reeva Steenkamp's death, Remuzzi said.
Pistorius is in no current Nike campaigns, and Remuzzi told UPI the footwear, apparel and sports-equipment company "thought [it] was appropriate to take down" from Pistorius' official website a 2011 Nike print ad of Pistorius at the start of a sprint race breaking out of the starting blocks to the phrase, "I am the bullet in the chamber," accompanied by Nike's signature Just Do It catchphrase.
The ad was removed from Pistorius' site Thursday.
Also Monday, Oakley Inc., a maker of sunglasses, sports visors and ski goggles, said in a statement, "In light of the recent allegations, Oakley is suspending its contract with Oscar Pistorius, effective immediately."