"I cannot say Pistorius's memory failure is suspicious but the mobile phones were clearly in use up to the time of the killing."
During the court hearing at which Pistorius was released on bail in March, prosecutor Gerrie Nel said examination of the mobile phones was vital.
Mr Nel said detectives had found four mobile phones on the bathroom floor: two BlackBerries and two iPhones.
Their position in the bathroom, close to the shower cubicle, could be evidence that the couple had a furious row during which Reeva had locked herself in.
Pistorius, who competed at the London Olympics last year against able-bodied athletes, told the court he had thought she was an intruder when he fired four shots from a handgun through the door.
Three hit Reeva and she bled to death.
Pistorius will next appear in Pretoria Magistrates' Court on August 19.
Text messages, together with a ballistics examination of the toilet cubicle and door, are believed to be the two pivotal elements of the prosecution's case.
- Mail On Sunday