Pretoria, South Africa (CNN) -- Model Reeva Steenkamp was shot four times through the bathroom door at the home of Olympian Oscar Pistorius, a South African official familiar with the case told CNN on Monday.

She was alive after she was shot and was carried downstairs by Pistorius, said the official, who was not authorized to release details to the media.

A blood-stained cricket bat has also emerged as key evidence in the case, according to the City Press newspaper of Johannesburg.

Detectives are working to determine whether the bat was used to attack Steenkamp or she used it in self-defense, the newspaper reported, citing a source with inside knowledge of the case. Detectives are also looking into the possibility that Pistorius used the bat to break down the bathroom door.

The details are the latest to emerge in the shooting death that has roiled the nation and left South Africans asking what went so terribly wrong inside the upscale Pretoria home of the man nicknamed "Blade Runner" for his lightning-fast prosthetic legs.

The official, who spoke on condition of anonymity, said there were indications the 29-year-old model intended to stay the night at the house: She had an overnight bag and her iPad.

Opinion: Pistorius case and the plague of violence against women

Authorities have released little about a possible motive in the Valentine's Day shooting, while local media have reported that Pistorius had mistaken his girlfriend for an intruder. South African authorities have stressed that the scenario did not come from them, and said there was no evidence of forced entry at the home.

Police have charged Pistorius with murder, and he will appear in court Tuesday for a bail hearing. South African prosecutors have said they intend to upgrade the charge to premeditated murder, but have not released further details.

Pistorius, 26, has rejected the murder allegation "in the strongest terms," his agent said in a statement.

Nike's bullet ad with Pistorius backfires

Burial service

The same day Pistorius returns to court, Steenkamp will be buried in a private service in her hometown of Port Elizabeth.

Her burial Tuesday will come two days after South Africa's national broadcaster aired a pre-recorded reality TV show featuring Steenkamp discussing her exit from "Tropika Island of Treasure," on which local celebrities compete for prize money.

The decision to air the program took "much deliberation," and "this week's episode will be dedicated to Reeva's memory," said Samantha Moon, the executive producer.

The shooting has stunned South Africa, where Pistorius is a national hero as the first disabled athlete to compete in the able-bodied Olympic Games. He competed in the London Games as well as winning two gold medals in the Paralympic Games.

Headlines about the case have dominated in the days since Pistorius was arrested, though tight-lipped authorities have revealed little about what, if anything, the track star has said.

Questions swirl

Reports say Pistorius and Steenkamp became an item around November and were popular in South African social circles.

The night before the shooting, Steenkamp appeared to be looking forward to Valentine's Day.

"What do you have up your sleeve for your love tomorrow?" she asked her Twitter followers the day before. "Get excited."

Steenkamp was found in a pool of blood at Pistorius' home Thursday morning. Neighbors alerted authorities to the early morning shooting, saying they had "heard things earlier," police spokeswoman Denise Beukes has said. She did not clarify what the neighbors reported they heard.

Authorities also have not said whether Pistorius called for help.

Pictures of his walk to a police car, his head covered by a sweatshirt, have flashed repeatedly across television screens.

On Sunday, Pistorius canceled his appearances in five upcoming races.

The move is meant to help Pistorius focus on the legal proceedings and "help and support all those involved as they try to come to terms with this very difficult and distressing situation," said Peet Van Zyl of Pistorius' management company, In Site Athlete Management.

CNN's Robyn Curnow reported from South Africa; Chelsea J. Carter and Faith Karimi reported from Atlanta.