Lawyers for South African athlete Oscar Pistorius have challenged the testimony of a senior police detective on the second day of a bail hearing.
The detective said a witness heard fighting at Mr Pistorius's home on the night he shot Reeva Steenkamp, 29.
But he changed details of his testimony under questioning, which Mr Pistorius' family said was "extremely concerning".
Mr Pistorius, a champion Paralympic sprinter, is charged with the premeditated murder of Reeva Steenkamp.
If denied bail, Mr Pistorius could face months in jail before a full trial is held later this year.
The evidence of veteran Detective Hilton Botha appeared first to boost the prosecution's case and then offer the defence team a hope of winning the argument, correspondents say.
At the end of a second day in court in Pretoria, the magistrate appeared to question Det Botha's assertion that Mr Pistorius could be a flight risk who should be denied bail.
The BBC's Andrew Harding, in court, says the magistrate's line of questioning indicated he may be considering granting bail.
In a statement, Mr Pistorius' family said they were "satisfied with the outcome of today's proceedings".
Under questioning from prosecution lawyer Gerrie Nel, Det Botha described the scene at Mr Pistorius's home after Ms Steenkamp was shot and killed.
He told the court that the trajectory of gunshots through the bathroom door indicated that Mr Pistorius, a double amputee, was wearing his prosthetic legs and shot downwards through the door.
"I believe that he knew that Reeva was in the bathroom and he shot four shots through the door," Det Botha told the court.
He said the holster for Mr Pistorius's 9mm pistol was found by the bed - a sure sign, he told the court, that the athlete must have known she was not in bed.
The testimony contradicted an earlier account given by Mr Pistorius.
He said he was walking on his stumps and grabbed his gun because he felt vulnerable when he thought an intruder had entered his home.
Det Botha also accused Mr Pistorius of having unlicensed ammunition for a 38mm weapon, and said bottles of testosterone and needles were also found.
But Det Botha then appeared to modify some crucial details.
He initially said a witness who heard screams and shots was some 600m (1,800ft) away, but later amended his answer to 300m after a break for lunch.
He admitted that Mr Pistorius's account of events, delivered via an affidavit read out in court on Monday, appeared to contain no inconsistencies.
The testosterone found was actually a legal herbal remedy used by athletes, the defence said.
The defence accused the investigator of bias, saying police disregarded evidence Mr Pistorius gave on the day of the shooting.
Mr Pistorius claims he was asleep until only moments before the shooting, that the bedroom was completely dark, and that there was no argument between the couple.
Det Botha conceded that it was dark and that curtains and blinds were closed in the bedroom when the shooting took place.
In their statement, the Pistorius family said Det Botha's answers confirmed that ballistic and forensic evidence was consistent with the athlete's version of events.
The family "trust that everyone has more clarity on this very tragic event," they said.
However, the statement added, the family finds "the contradictions in [Det] Botha's testimony extremely concerning".
Detail about the aftermath of the shooting also emerged as Det Botha answered questions.
He said he arrived at the house at 04:15 on 14 February, and found Ms Steenkamp lying dead on the ground floor.
She was wearing white shorts and a black vest and was covered in towels, he said.
A lawyer and Mr Pistorius's brother were already at the scene.
Ms Steenkamp was shot in the right side of her head, her right hip and her right elbow, Det Botha said.
He agreed the post-mortem examination had showed no signs of assault or defensive wounds on Ms Steenkamp.
On Tuesday, Mr Pistorius told the court he had woken in the middle of the night and heard what he thought was an intruder in the bathroom.
He shot through the door and only then realised Ms Steenkamp was not in bed.
He said he was "absolutely mortified" at her death.
The magistrate has deemed this a "schedule six" case, meaning Mr Pistorius is accused of premeditated murder.
His defence team will have to prove the extenuating circumstances that would justify granting bail.
The first day of the hearing on Tuesday coincided with Ms Steenkamp's funeral.
The model and law graduate was cremated in her home town of Port Elizabeth where her father, Barry Steenkamp, told reporters: "We have to keep Reeva in our hearts for ever."
Oscar Pistorius won gold medals at the 2004 Paralympic Games in Athens, in Beijing in 2008 and London in 2012.
In London he made history by becoming the first double-amputee to run in the Olympics, making the semi-final of the 400m.