Oscar trial - what we know so far

Oscar Pistorius outside court. (Media24)

Pretoria - Prosecutors expect to wrap up their murder case against Oscar Pistorius early next week after calling "four or five" more witnesses, they said on Wednesday.

Attempting to prove the world-famous double-amputee athlete intentionally killed girlfriendReeva Steenkamp and is also guilty of three other firearms-related charges, the prosecution has called 18 witnesses so far; police investigators, neighbours, a security guard, some of Pistorius's friends, a former girlfriend and a firearms trainer who was selling Pistorius more guns.

A look at the prosecution's case in the first two-and-a-half weeks of the trial:

The fight

Crucial for prosecutors is their allegation that Pistorius fought with his girlfriend and had a motive before he shot her three times through a toilet door in a bathroom in his home.

Three neighbours testified to hearing a woman screaming in the pre-dawn hours of 14 February last year. A fourth said she heard a woman arguing.

Through police photographs of the blood-spattered scene, prosecutors have presented other evidence to suggest an argument: damage to Pistorius's bedroom door, broken tiles in the bathroom and a bashed in metal panel, also in the bathroom.

There were blood spots in the bedroom away from where Pistorius likely would have carried Steenkamp when he says he took her to get help.

Pistorius says he was the only person to scream desperately for help after realising he had shot Steenkamp by mistake.

Chief defence lawyer Barry Roux cited noise tests that he says will show that neighbours are mistaken that they heard Steenkamp, and says he'll also show Pistorius screams in a high-pitched voice when extremely anxious.

The defence hasn't yet explained the damage to the bedroom door, bathroom tiles and metal panel.

Jerusha Sukhdeo-Raath takes a look at the prosecution's case in the first two-and-a-half weeks of the trial. Watch.

The shooting

Police ballistics expert Captain Christiaan Mangena testified on Wednesday that Steenkamp was standing inside the toilet cubicle and facing the closed door when she was hit by the first bullet. Mangena said Steenkamp was shot in the right hip first, the second bullet missed, and the last two bullets hit the 29-year-old model in the arm and head.

He couldn't determine the order of the last two shots.

But by saying the hip shot and miss were first, Mangena's analysis appeared to support the prosecution's claim that the earliest shots were not immediately deadly and Steenkamp would have screamed out, meaning Pistorius should have known who he was shooting at.

Defence experts will show Pistorius shot four times with two "double-tap" bursts, lawyer Roux said, and Steenkamp wouldn't have had time to scream.

Roux also disputed Mangena's shot sequence.

Initial cover-up

Housing estate security guard Pieter Baba said he had two phone calls with Pistorius after neighbours reported gunshots from the runner's house.

Baba testified Pistorius told him everything was "fine" in the first call then phoned back moments later, cried and hung up.

The defence cast doubt on Baba's recollection of events by producing phone records that they said showed Pistorius called the guard first, but couldn't speak because he was so distraught.

He then called Baba back, defence lawyers said.

Still, Baba was certain of the words Pistorius spoke to him after the shooting: "Mr Pistorius said to me, security, everything is fine," Baba testified.

Pistorius’s character

Prosecutors have scrutinised previous gun incidents involving Pistorius in relation to two other charges he faces for allegedly shooting in public, but the details have also been used to try to show Pistorius was reckless and sometimes angry and could have shot Steenkamp intentionally.

Two witnesses, one a former girlfriend, say Pistorius fired a shot out the open sunroof of a moving car in 2012 after an altercation with traffic police.

In another incident, friends say a gun Pistorius was handling in a restaurant fired and the Olympian asked someone else to take the blame, with prosecutors trying to show that Pistorius is also dishonest.

Pistorius completely denies the sunroof shooting and says the restaurant shooting was not his fault because his friend hadn't warned him the gun he was passing was "one-up," or had a bullet in the chamber.

Bungled investigation

Pistorius's defence says the police investigation was flawed.

While prosecutors used a sequence of dozens of photos to show to the court the bloody and sometimes grisly shooting scene, Roux has pointed out police errors throughout.

In one, Roux got a senior policeman to tell how another officer picked up Pistorius's gun and started handling it and maybe even cocking it at the scene without forensic gloves.

Roux also says defence experts will show marks on the toilet door which police investigators missed and which show Pistorius's version to be true that he tried to kick the door down with his prosthetics to help Steenkamp after realising his mistake.