Video report by ITV News Africa correspondent Rohit Kachroo
Oscar Pistorius fired his pistol out of a car's open sun-roof after an argument with a police officer, ex-girlfriend Samantha Taylor told a court.
On the fifth day of his trial for the murder of Reeva Steenkamp the 27-year-old South African Olympic athlete's former girlfriend revealed her testimony at Pretoria High Court.
She decribed how Pistorius shouted at a policeman after the car they were driving in was pulled over for speeding, south of Johannesburg in September 2012.
After seeing Pistorius' pistol lying on the car seat, the officer picked it up and emptied its magazine onto the floor of the car, prompting an outburst from Pistorius, Taylor said.
When they were allowed to go on their way, Pistorius and the driver, a friend called Darren Fresco, started to joke about shooting out a traffic light, known in South Africa as a robot, Taylor said.
She was was sitting in the back seat at the time of the incident.
The testimony from Taylor comes two days after the court heard how Pistorius accidentally fired a pistol under the table in a packed Johannesburg restaurant - right next to a child - and then asked his friend Fresco to take the blame.
As well as being charged with the murder of Steenkamp, his girfriend, on Valentine's Day 2013, Pistorius is facing three firearms offences, part of prosecution attempts to portray him as a gun-obsessed hot-head.
Pistorius denies murder, saying he mistook Steenkamp for an intruder when he fired four shots through a locked toilet door in his luxury Pretoria home.
If found guilty, he is likely to spend at least 25 years behind bars.
Samantha Taylor described an occasion when Pistorius jumped out of his car at the gateway of his Pretoria housing complex and put his gun to the window of a black BMW that appeared to have been following him.
Taylor also said Pistorius woke her up in the middle of the night after hearing a bang in the bathroom, and then "got his gun and walked out of the room."
Pistorius kept his gun on him "all the time", his ex-girlfriend Samatha Taylor told the court
His ex-girlfriend also said he cheated on her with Reeva Steenkamp, and their relationship ended a second time when he took Reeva to an award ceremony.
She says they started dating in 2011 when she was 17.
She also said there were "one or two" other occasions when Pistorius woke her after hearing noises during the night.
Pistorius said he did not check whether Steenkamp was still in the bed, or make any move to wake her before moving to the bathroom and shooting the supposed intruder on the night he shot her.
After the emotional testimony of Samantha Taylor, the court heard the testimony of Peter Baba, a security guard at the estate where Pistorius lived and where he shot his girlfriend Reeva Steenkamp.