Prosecutor Gerrie Nel said the prosecution team had a witness who heard shouting coming from the property at the exclusive Silver Lakes Golf Estate between 2am and 3am.
Shortly afterwards Reeva Steenkamp, 29, lay bleeding to death in Pistorius's bathroom hit by three bullets, one in the head, the hip and arm, Pretoria Magistrates' Court heard.
Pistorius has admitted shooting her with a 9mm pistol but said he thought a burglar or burglars were in the bathroom and he did not intend to shoot the model.
The athlete has said he believed intruders were in his house so he fired through the bathroom door in the dark as he was too scared to turn the light on.
Discovering his mistake, he broke the door down with a cricket bat and carried her downstairs, he has said.
But today, the second day of his bail application, investigating officer Hilton Botha said the prosecution also have a witness who said the lights were on after hearing gunshots.
Lawyers and police studied plans of the bedroom and bathroom.
A projector was used to beam the plans up for the public and press to see.
Mr Botha said there was "no way" he believed Pistorius's version of events.
The runner has said he shot through the door while on his stumps but the court heard the bullets' trajectory was through the top of the door.
Mr Botha said he believed the bullets were fired down, suggesting that Pistorius was wearing his prosthetic legs when the shots were discharged.
He said: "I believe he knew she was in the bathroom and he shot four shots through the door."
The court heard that two mobile phones were seized at the property and neither had been used to call the police or paramedics.
The court also heard today that two boxes of testosterone and needles were found in Pistorius's bedroom.
And details were released of a row he allegedly had with a man over a girl at Kyalami racetrack where Pistorius allegedly threatened to "f*** up" the rival.
It was also claimed he was involved in another shooting at a restaurant in Johannesburg in January and asked the gun owner to take responsibility for the incident.
Mr Botha said he wanted Pistorius charged additionally with a weapons violation after unlicensed .38 calibre ammunition was found at the house.
The athlete - who was sobbing this morning in court - made notes with a silver pen as the case progressed.
He told officials he had been a victim of crime and received death threats, but today the court heard there were no records of this.
In an affidavit, Pistorius has denied murdering the law graduate at his home in the early hours of Thursday.
He has said they were in love and he thought Miss Steenkamp was in bed when he got up in the dark and blasted through the door.
Pistorius's lawyer Barry Roux said it was not testosterone but a herbal remedy discovered in his client's bedroom.
Cross-examining Mr Botha, Mr Roux said a post-mortem examination showed Miss Steenkamp's bladder was empty.
He said that was consistent with her getting up at 3am to go to the toilet.
Mr Roux asked repeatedly why the police did not make simple checks - over the lighting and whether Pistorius had other phones.
The lawyer said Pistorius phoned the housing complex manager for help at 3.19am then Netcare hospital a minute later.
Mr Roux said the police discarded anything that might have been consistent with a defence.
Officers found the victim covered in towels and wearing white shorts and a black top.
Prosecutors believe Pistorius, who won two gold medals and a silver at London's 2012 Paralympic Games, is a flight risk and oppose bail.
Mr Botha said Pistorius, who underwent below-the-knee amputations when he was 11 months old, has offshore accounts and a property in Italy.
One witness said he heard a shot, followed 17 minutes later by more shots, Mr Botha said.
"One of our witnesses heard a fight, two people talking loudly at each other ... from two in the morning to three," he said, adding that the witness was about 1,000ft away.
Members of the Women's League of the ruling African National Congress protested outside the red-brick court, waving placards saying "No Bail for Pistorius" and "Rot in jail".
The case has stunned sports fans worldwide.
But it has been felt most acutely in South Africa, where Pistorius was seen as a hero who transcended racial divides that persist nearly 20 years after the end of apartheid.
He carried South Africa's flag at the closing ceremony of the London Olympics, and American magazine Sports Illustrated named him as one of the most inspiring figures of the year.
The sprinter's endorsements and sponsorships included Nike, telecoms firm BT, sunglasses maker Oakley and French designer Thierry Mugler and were thought to be worth as much as two million US dollars (£1.3 million) a year.
Nike and Mugler both said they have dropped Pistorius from advertising campaigns, and Clarins cosmetics firm said it was recalling its A Man perfume range out of "respect and compassion towards the families involved".
The hearing was adjourned to tomorrow morning when a decision over bail might be made.
The court will resume at 11am in Pretoria, 9am GMT.
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