Reeva Steenkamp's cousin Kim Martin has labelled Oscar Pistorius a "psycho" for killing the South African model.

The six-time Paralympic champion was sentenced to five years in prison yesterday for the culpable homicide (manslaughter) of Steenkamp.

The double amputee claimed that he mistook his girlfriend for an intruder when he fired four gunshots through a toilet door at his home in Pretoria in the early hours of Valentine's Day last year.

Ms Martin, who told the High Court last week that Pistorius deserved a custodial sentence, believes that the 27-year-old killed Steenkamp in a "blind rage".

"My cousin would only take her phone to the toilet and lock the door if she was trying to get help," The Mirror quotes Ms Martin as saying. "What kind of psycho must he be to flip out like that?"

Ms Martin has also admitted that she will be haunted by the fact that she never discovered the truth about Reeva's concerns after she told her that they "need to talk" when asked if she was "happy" with Pistorius.

The athlete's defence team has stated that Pistorius may spend 10 months in jail before serving the rest of his sentence under house arrest.