Pretoria - Oscar Pistorius' ex-girlfriend told his trial he once fired his gun from his car sunroof after becoming angry with police. An emotional day in court then climaxed with testimony from a security guard shocked to find Mr Pistorius carrying a dying Reeva Steenkamp. The athlete had earlier told him "everything is fine" when he rang him after shots were heard. Mr Pistorius denies both murdering Ms Steenkamp and shooting from his car. Early in her testimony, former girlfriend Samantha Taylor broke down while discussing two break-ups with the athlete. She said Mr Pistorius had twice been unfaithful, with the relationship finally ending when he "cheated" on her with Reeva Steenkamp. The defence pointed to emails it said proved the relationship with Ms Taylor was already over by the time Mr Pistorius began seeing Ms Steenkamp, but Ms Taylor insisted the relationship was not "officially" over when he started dating Ms Steenkamp. The model also said the alleged shooting incident happened when he became angry after a police officer stopped him for speeding, saw the gun on the car seat and told him it could not be left there. She accepted that he laughed around the time he actually fired the gun. Ms Taylor testified that Mr Pistorius kept his gun "on him all the time," and described him as a man who could get very angry. Pieter Baba, a security guard working at Oscar Pistorius' gated community, the Silverwoods Country Estate, followed Ms Taylor in the witness box. He said the athlete told him everything was "fine" when he called to investigate neighbours' reports of gunshots on the night Reeva Steenkamp was killed. He said he made the phone call from outside the runner's villa, before dawn. His said Mr Pistorius then called him back, crying but not saying anything, before the line went dead. When he saw Mr Pistorius carrying a dying Reeva Steenkamp down the stairs, Mr Baba said he was initially too shocked to help. Mr Pistorius looked at the floor while Pieter Baba gave his evidence, at one point appearing to cry when the security guard described the bloody scene he found.  Mr Pistorius claims he shot Ms Steenkamp after mistaking her for an intruder, and had not attempted to wake her before picking up his gun. If found guilty, the 27-year-old double amputee, dubbed the "blade runner", could face life imprisonment. (FA)