Using the toilet or hiding?
Chief investigating officer Det Hilton Botha claimed that Mr Pistorius fired at an angle into the toilet door, and that Ms Steenkamp's wounds suggested she was not on the toilet - which adjoins the bathroom - at the time, but cowering in a corner.
Defence lawyer Barry Roux said that Steenkamp's bladder was empty when she died, indicating she had indeed got up to use the toilet. Mr Roux said Steenkamp's autopsy showed no sign of defensive wounds or an assault.
Was Mr Pistorius wearing his prosthetic legs? The prosecution has linked this question to which he was acting in a pre-meditated fashion.
Prosecutor Gerrie Nel claims that on the night of the killing Mr Pistorius got up, paused to put on his prosthetic legs, walked seven metres (24ft) and fired his gun four times through the locked toilet door.
But the defence say he was unable to attach his prosthetic limbs in time to confront the perceived threat.
Det Botha testified that he thought the bullets were fired "down", suggesting Mr Pistorius did have his prostheses on. But he admitted he had no actual evidence of that, and could not be sure about the distance the shots were fired from or their precise trajectory.
According to Mr Pistorius's affidavit, he was walking on his stumps - making him feel "extremely vulnerable" in the "pitch dark".
Asleep in the dark - or arguing?
But was it dark?
Mr Pistorius's testimony relies on it having been dark, because Mr Pistorius says he did not notice that Ms Steenkamp was not in bed - despite having to walk twice past the bed to get to the bathroom from the balcony and back.
It would have been even more difficult not to notice Mr Steenkamp's absence, Det Botha claimed, because the pistol was under the side of the bed on which she was sleeping.
"You want to protect her but you don't look at her?" Mr Nel asked the athlete as he sobbed quietly.
The prosecution says a witness alleges the lights were on, and that a woman's cries could be heard.
"We have statement of a person who said after he heard gunshots, he went to his balcony and saw the light was on. Then he heard a female screaming two-three times, then more gunshots," Det Botha told the court.
Mr Botha also cited a female witness who said that she heard "non-stop talking like fighting" between 02:00 and 03:00 on 14 February.
The detective initially told the court the witness was some 600m (1,800ft) away, but later amended his answer to 300m - something the Pistorius family said was "extremely concerning".
Det Botha was forced to acknowledge that while the witness had said she heard two sets of three shots 17 minutes apart, only four cartridges were found.
In a statement read out to court, Mr Pistorius said that he was "filled with horrible fear" that someone had sneaked in through an open window of the bathroom in the dead of night.
Det Botha said four mobile phones were seized at the property, but none was used to call police or paramedics.
Mr Roux said there was another phone which the defendant had used to call for medical help at 03:20. He had also called a security guard. Det Botha said he had not been told about the other phone.
Two boxes of testosterone and needles were found in Mr Pistorius's bedroom, the prosecution says.
The defence says it was not testosterone, but a legal "herbal remedy" used by athletes.
Det Botha said Mr Pistorius would also face charges of possession of unlicensed ammunition, since the police found .38 rounds in a bedroom safe. Mr Pistorius has a licence for a 9mm pistol, not a .38.
The ammunition belonged to Mr Pistorius's father, the defence says.
Mr Pistorius has offshore accounts and a house in Italy, and thus constitutes a flight risk, the prosecution argues.
"We don't want another Dewani matter," Det Botha told Mr Pistorius's bail hearing, referring to the case of Shrien Dewani, the British man accused of the murder of his wife. South Africa is currently trying to extradite him from the UK.
But the magistrate seemed sceptical about whether Mr Pistorius constituted a flight risk, asking Det Botha whether a gold medal-winning Olympic athlete would forsake his career and avoid the chance to clear his name in court.http://www.bbc.co.uk/news/world-africa-21516664