The defence in the murder trial of Oscar Pistorius has been postponed until 7 April as one of the assessors assisting the judge has been taken ill. 
 
 The athlete had been expected to take the stand on Friday. 
 
 The trial, in the South African city of Pretoria, has already heard 15 days of prosecution-led testimony. 
 
 Mr Pistorius denies deliberately shooting his girlfriend, Reeva Steenkamp, in February 2013, saying he mistook her for an intruder. 
 
 Prosecutors allege that he killed her after an argument. 
 
 Analysis There are no juries in South Africa's legal system but in serious High Court cases, two assessors are assigned to help the judge evaluate the case and act as additional eyes and ears. They are usually lawyers or retired magistrates but they can also be lay people. For the sake of continuity and in the interest of justice, the same assessors need to be present for the entire trial. In the event that both assessors disagree with a judge's verdict they can overrule her. But in the case of lay assessors, the judge's legal experience counts in her favour and her decision carries more weight. Both assessors in the Pistorius case are lawyers so they are crucial in ensuring justice. The justice department explains that a judge does not have to listen to the assessors' opinions but they usually help the judge to reach a decision. 
 
 Judge Thokozile Masipa, announcing that the assessor was ill, said that in her absence the court was "not properly constituted". 
 
 The judge suggested the date of 7 April to resume the trial, which both prosecution and defence teams accepted. 
 
 Under South African law, there is no jury system and two assessors, normally lawyers or retired magistrates, help the judge reach a decision in serious cases. 
 
 The BBC's Karen Allen in Pretoria says that, although Mr Pistorius is not legally obliged to testify, he is the only witness to the alleged murder and is expected to testify when the trial restarts. 
 
 His lawyers had previously told journalists that it was "likely" they would call him to give evidence first, she adds. 
 
 Prosecution testimony has relied on accounts from neighbours and specialist ballistics, forensic and mobile phone evidence. 
 
 Our correspondent says the defence had been due to address key questions, in particular: 
 
 Allegations from witnesses that Mr Pistorius was reckless with guns and had fired a pistol indiscriminately on two occasions in the past 
 
 Why he didn't check the whereabouts of Ms Steenkamp when he feared an intruder was in the house 
 
 Why, as a person used to handling weapons, he didn't fire a warning shot 
 
 Image caption Oscar Pistorius denies the murder of Reeva Steenkamp 
 
 Ms Steenkamp, a model, reality TV celebrity and law graduate, was hit by four bullets while in the toilet cubicle of Mr Pistorius' home in Pretoria. 
 
 People who were in the area on the night of the shooting have told the court they heard screams, shots and bangs. 
 
 However, Mr Pistorius has said he believed Ms Steenkamp was in bed when he shot at the toilet door, thinking an intruder was about to attack them. 
 
 Mr Pistorius is a double amputee who holds six Paralympic medals and competed in the 2012 Olympic Games. 
 
 If found guilty, the 27 year old - dubbed the "blade runner" because of the prosthetic limbs he wore to race - could face life imprisonment. ||||| PRETORIA, South Africa (AP) — The judge in the murder trial of Oscar Pistorius has delayed proceedings until April 7. 
 
 FILE - In this Saturday, Sept. 8, 2012 file photo, South Africa's Oscar Pistorius wins gold in the men's 400-meter T44 final at the 2012 Paralympics, in London. The man who racing commentators said was... (Associated Press) 
 
 FILE: In this file photo taken Monday March 10, 2014, Oscar Pistorius cries as he listens to cross questioning about the events surrounding the shooting death of his girlfriend Reeva Steenkamp, in court... (Associated Press) 
 
 FILE: In this file photo taken Monday, March 24, 2014, Oscar Pistorius, cries in court as he listens to evidence being given in Pretoria, South Africa, in the murder trial for the shooting death of his... (Associated Press) 
 
 Judge Thokozile Masipa said Friday that one of her two assessors, legal experts who are helping her with the case, was unwell and that the trial had to be delayed. 
 
 Defense lawyers for the double-amputee runner who killed his girlfriend last year were due to begin their case on Friday after four weeks of prosecution-led testimony. 
 
 Pistorius says he shot Reeva Steenkamp by accident, mistaking her for an intruder in his home. Prosecutors say he killed her after an argument.
– Oscar Pistorius had been expected to take the stand in his murder trial today, but the beginning of the defense case has now been delayed until next month. Judge Thokozile Masipa says one of two legal experts helping her with the case is sick and the trial has been suspended until April 7, reports the AP. The athlete's defense lawyers had been set to begin their case today after four weeks of testimony from the prosecution. Pistorius is not legally obliged to testify, but he was expected to take the stand today as the only witness to girlfriend Reeva Steenkamp's death, the BBC notes. He says he shot her after mistaking her for an intruder. When the trial resumes, the defense is expected to address key issues including his alleged past carelessness with firearms and why he failed to check on his girlfriend's whereabouts when he believed there was an intruder in the house.