The murder trial of South African Paralympian Oscar Pistorius focused Tuesday on whether neighbours could have heard his model girlfriend screaming on the night he allegedly shot her dead.
Prosecutors are trying to prove that Reeva Steenkamp did scream and that this showed the star athlete known as the "Blade Runner" knowingly gunned her down in a fit of anger after a row in the early hours of Valentine's Day last year.
The defence claims Pistorius shot the 29-year-old model and law graduate four times through a locked toilet door after mistaking her for an intruder and that any screams came from the double-amputee sprinter himself.
State prosecutor Gerrie Nel attempted to show that tests conducted by engineer and acoustics expert Ivan Lin backed up the premeditated murder charge, arguing that neighbours who lived 177 metres (yards) from Pistorius could have been able to differentiate between a male and a female screaming.
Nel submitted Lin to a technical cross-examination a day after a panel of mental health experts said the 27-year-old Pistorius did not suffer from a mental disorder when he shot Steenkamp and could be held "criminally responsible" for his actions.
Lin said on Monday that at 177 metres away "it is very unlikely a listener can hear a scream let alone interpret the sound source reliably".
However, Nel insisted that Lin, a carefully spoken man in black-framed glasses, failed to do his sound estimates properly, saying he did not take into account factors that would have made it possible for the neighbours to clearly hear Steenkamp.
"We have four people identifying the sound of a woman's voice, we have no exceptions," Nel said.
"I do believe they heard a sound but I cannot say whether they were correct or incorrect, it's not for me to interpret that," said Lin.
Later, Nel asked Lin if he thought the state's witnesses were lying. "Not at all," he replied.
The Pistorius trial started in March and has attracted global media attention. He has pleaded not guilty to Steenkamp's murder, a charge which risks 25 years in prison, and other charges related to ammunition possession.
Judicial sources say once all the evidence has been presented -- estimated to last through the week -- the defence and prosecution will require a few more weeks to compile their written submissions before presenting them to court.
They will return to court to answer final questions on their arguments.
South Africa does not have jury trials, so a verdict will be delivered by the judge after a few weeks' deliberation.