Botha was further forced to admit that police hadn't seen a bullet that hit the toilet basin in their investigation. The defence's forensic team discovered the bullet four days later.
He also conceded he did not wear protective clothing when Pistorius' forensic team visited the house, which may have contaminated the scene.
The first double amputee to compete against able-bodied athletes in the Olympics in London last year says he shot Steenkamp by mistake through a locked bathroom door, believing she was a burglar.
She had wounds to her head, elbow and hip.
Medics found her covered in bloodied towels and wearing white shorts and a black vest. She was declared dead on the scene.
Prosecutors later backtracked on the charge that a police search of Pistorius's home found testosterone and needles in a dresser in his bedroom.
"We can't tell what it is," said national prosecuting authority spokesman Medupe Simasiku later said. "We can't confirm or deny it until we get the forensic report."
The athlete, who off the track has had a rocky private life with stories of rash behaviour, beautiful women, guns and fast cars, has built up a powerful team of lawyers, medical specialists and public relations experts for his defence.
They have to neutralise his reputation for public outbursts and flirts with danger.
In 2009 he admitted to a newspaper that he slept with a pistol, machine gun, cricket bat and baseball bat for fear of burglars.
Pistorius revealed he earned 5.6 million rand ($640,000) a year and owned the $570,000 house where the killing took place as well as two other homes.
His career has been put on hold since the shooting, forcing him to cancel races in Australia, Brazil, Britain and the United States between March and May.
Two of his American sponsors, Nike and sunglasses maker Oakley, announced they were dropping Pistorius from their advertising campaigns, which have earned him millions of dollars in endorsements.
