Gerrie Nel accused the athlete of being a “deceitful witness” who told the court a “snowball of lies”.
Pistorius denies murdering his girlfriend Reeva Steenkamp.
He says he mistook her for an intruder but the prosecution says he deliberately shot her after a row.
Prosecutor Gerrie Nel made his concluding remarks , with the defense due to follow.
Known as the “Pitbull” prosecutor, Nel said that even if Pistorius’s account of events were true, “he cannot escape” a conviction for murdering with intent.
Steenkamp was killed at Pistorius’s home in South Africa’s capital, Pretoria, on February 14 last year.
At the court in Pretoria, Nel began his closing argument by accusing the athlete’s lawyers of presenting two lines of defence that “can never be reconciled”.
Pistorius said he had fired both involuntarily and also out of fear, Nel argued, insisting the court had to choose only one of his defences.
He said the court “should have no difficulty in rejecting” the athlete’s version of events because it was “devoid of any truth”.
Pistorius’s defence team led by top lawyer Barry Roux has sought to present the athlete as a vulnerable individual.
Roux argued that the athlete’s disability had fostered a “heightened fight response” to compensate for not being able-bodied, and that his insecurities led him to confront danger.