The Olympic and Paralympic athlete is on trial for the murder of 29-year-old model and law graduate Steenkamp on Valentine’s Day 2013.
He has pleaded not guilty to murder, saying he was deeply in love with Steenkamp, who he had been dating for a few months, and that he mistook her for an intruder hiding in a toilet at his luxury Pretoria home.
However, text messages between the pair in the weeks leading up to the shooting painted a picture of a volatile, stormy relationship, with Steenkamp accusing Pistorius of continual jealousy and outbursts of anger.
“I’m scared of you sometimes and how you snap at me and of how you will react to me,” one message sent by Steenkamp on January 27, 2013, said.
As police expert Francois Moller read out the messages to the court on Day 14 of the trial, Pistorius sat in the dock, his head buried in his hands.
“We are living in a double standard relationship. Every five seconds I hear about how you dated another chick. You really have dated a lot of people yet you get upset if I mention one funny story with a long-term boyfriend,” the Steenkamp message continued.
“You make me happy 90% of the time and I think we are amazing together but I am not some other bitch you may know trying to kill your vibe.”
Moller said he had analysed thousands of mobile phone messages sent between the couple found and 90 percent of them to be normal, often loving, interactions.
However, another exchange backed up the testimony of an earlier witness who said the 27-year-old athlete fired a pistol under a table in a packed Johannesburg restaurant and then asked his friend to take the blame.
“Angel please don’t say a thing to anyone. Darren told everyone it was his fault. I can’t afford for that to come out. The guys promised not to say a thing,” the message sent by Pistorius on January 11, the day of the incident, said.
“I have no idea what you’re talking about,” Steenkamp replied, ending the message with a smiley face.
The court adjourned for the day before Moller concluded his evidence, leaving the gallery waiting for messages between the couple in the days and hours before the killing.
Prosecutors are seeking to prove Pistorius tried to kill Steenkamp deliberately by firing four rounds from a 9 mm pistol through a locked toilet door after a heated argument.
Throughout the trial, they have tried to portray him as a gun-obsessed hot-head, who also fired a handgun through the open sun-roof of a car after an argument with a policeman.
The state is expected to wrap up its case this week, although a slew of defence witnesses waiting in the wings suggests the trial is likely to run into May.
The delays and extra expenses have forced Pistorius to sell the luxury Pretoria home in which he killed Steenkamp so he can pay his mounting legal fees.
Pistorius’ lower legs were amputated as a baby but he went on to achieve global fame as the “fastest man on no legs”, running on carbon-fibre prosthetic limbs to win gold medals at the Beijing and London Paralympics.
Nicknamed the “Blade Runner”, he also won a battle against athletics authorities for the right to compete against able-bodied men, becoming the first amputee runner at an Olympics when he reached the 400 metres semi-finals at London 2012.
His sporting feats and good looks made him one of the world’s most marketable athletes but lucrative deals with brands such as Nike and eyeware maker Oakley were dropped when murder charges were brought against him.
(Writing by Joe Brock; Editing by Ed Cropley and Alison Williams)