Chief prosecutor in Oscar Pistorius murder trial questions acoustics expert about screams

Oscar Pistorius arrives at court in Pretoria, South Africa, Tuesday, July 1, 2014. The murder trial resumed Monday June 30 after one month during which mental health experts evaluated the athlete and determined he did not have an anxiety disorder that could have influenced his actions on the night he killed his girlfriend Reeva Steenkamp. (AP Photo/Jerome Delay) (The Associated Press)

June Steenkamp, mother of Oscar Pistorius' girlfriend Reeva, arrives at court in Pretoria, South Africa, Tuesday, July 1, 2014. The murder trial of Pistorius resumed Monday June 30 after one month during which mental health experts evaluated the athlete and determined he did not have an anxiety disorder that could have influenced his actions on the night he killed his girlfriend. (AP Photo/Jerome Delay) (The Associated Press)

PRETORIA, South Africa – Testimony in the murder trial of Oscar Pistorius is focusing on the screams that neighbors heard on the night that the athlete killed girlfriend Reeva Steenkamp.

Chief prosecutor Gerrie Nel on Tuesday questioned an acoustics expert who had been called by the defense team as part of its effort to suggest some neighbors who testified they heard the screams of a woman were wrong, and that they actually heard the high-pitched screams of the double-amputee runner.

Pistorius fatally shot Steenkamp through a closed toilet door in his home in the early hours of Feb. 14, 2013.

He has testified that he fired in the mistaken belief there was a dangerous intruder in his home. The prosecution has alleged that Pistorius killed Steenkamp after a Valentine's Day argument.