Defence lawyer Barry Roux begins final arguments in the murder trial of Oscar Pistorius

Defence lawyer Barry Roux began his final arguments in the murder trial of Oscar Pistorius on Thursday.

The athlete is charged with the "wilful and intentional murder" of Reeva Steenkamp after he shot his then girlfriend dead at his home on February 14, 2013.

Pistorius has always maintained his innocence, insisting that he mistook Ms Steenkamp for an intruder after hearing a noise in the bathroom

After telling the North Gauteng High Court in Pretoria that the defence team would outline several crucial points which the State had ignored in attempting to prove its case against the Paralympian, Roux began by challenging the state's assertion the athlete only cited anxiety when it suited him.

"An anxious person does not walk around showing vulnerability," said Roux.

He said anxiety was triggered by a situation of distress.

This was a direct response to state prosecutor Gerrie Nel having argued that the defence team had failed to provide factual evidence that Pistorius screamed in a high pitched tone when nervous.

Roux said the state had only introduced the evidence of two neighbouring couples who claimed to have heard the screams of a woman coming from Pistorius's home.

Other neighbours had, however, testified that they heard the cries of a man.

"The State failed to dispute the arguments of two immediate neighbours," Roux said.

Roux also said the State had failed to clarify whether the sounds Pistorius's neighbours claimed to have heard on the night of the shooting were from the athlete's cricket bat as he tried to knock down the toilet door, or whether they had come from his gun.

Roux finished his argument for the day by pointing out there was a difference between the reliability and the credibility of witnesses.

He said that witnesses made honest mistakes and believed their own versions of events.

The trial continues.