Oscar Pistorius murder trial: Cross-examination into 4th day

Oscar Pistorius is being cross-examined at his murder trial for the fourth day by chief prosecutor Gerrie Nel.

Pistorius is into his second week of testimony Monday as he attempts to convince a South African judge that he killed girlfriend Reeva Steenkamp by mistake in the pre-dawn hours of Valentine's Day last year.

Pistorius' story has come under intense scrutiny from Nel, who argues that the double-amputee Olympian's version of the shooting on Feb. 14, 2013 is a lie.

Pistorius testified last week that he mistook Steenkamp for an intruder about to attack him when he fired four shots through a closed toilet door in his bathroom. The prosecution says the couple argued and Steenkamp fled to the toilet cubicle screaming before the athlete shot her intentionally.