The judge has been delivering her verdict in the Paralympic champion's murder trial at the High Court in Pretoria today.
During the six-month trial, the 27-year-old told the court in South Africa that he armed himself with a gun when he thought that an intruder had entered his home in the early hours of February 14 last year.
In his testimony, Pistorius said that after he entered the bathroom, "before [he] knew it [he] had fired four shots" at the toilet door behind which Steenkamp was standing.
Judge Masipa has questioned Pistorius's statement by claiming that he did not make it clear whether he intended to shoot or not and described the athlete as a "very poor and evasive witness".
She told the court that the six-time Paralympic gold medallist stated that the shooting was an accident and he did not have time to think about his actions.
Judge Masipa went on to say that Pistorius claimed that he did not fire on purpose, but pointed his firearm at the toilet door when he got a fright.
Pistorius denies deliberately murdering his girlfriend by claiming that he mistook the South African model for an intruder when he fired four gunshots through the toilet door at his home in Pretoria.