The defence in the murder trial of Oscar Pistorius is due to begin setting out its case, with the athlete himself expected to take the stand.
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.
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.
His lawyers have 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 will have to address key questions, in particular:
- Allegations from witnesses that Oscar 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
Ms Steenkamp, a model, reality TV celebrity and law graduate, was hit by four bullets while in the toilet cubicle of Mr Pistorius’s 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.
There are no juries at trials in South Africa, and his fate will ultimately be decided by the judge, assisted by two assessors.
If found guilty, the 27 year old – dubbed the “blade runner” because of the prosthetic limbs he wore to race – could face life imprisonment.
Mr Pistorius said in his statement at the start of the trial that he woke in the early hours and walked on his stumps to the balcony, pulled in two fans, closed the sliding door and drew curtains. He said that shortly before he had spoken to Reeva, who was in bed beside him.
He said he rejected prosecution claims that a witness heard arguing coming from the house before the shooting.
2. Bathroom noise
Mr Pistorius said he heard the bathroom window sliding open and believed that an intruder, or intruders, had entered the bathroom through a window which was not fitted with burglar bars.
“Unbeknown to me, Reeva must have gone to the toilet in the bathroom at the time I brought in the fans,” he said.
Mr Pistorius said he approached the bathroom armed with his firearm, to defend himself and his girlfriend, believing Ms Steenkamp was still in bed.
Both sides agree four bullets were fired. Ms Steenkamp was hit three times.
Mr Pistorius said he fired his weapon after hearing a noise in the toilet which he thought was the intruder coming out of the toilet to attack him and Ms Steenkamp.
He said he was in a fearful state, knowing he was on his stumps and unable to run away or properly defend himself.
Mr Pistorius said he rejected claims that he was on his prostheses when he shot at the door.
A witness told the trial she woke to hear a woman screaming and a man shouting for help. She said that after the screams she heard four shots.
At his bail hearing last year, Mr Pistorius said he went back to the bedroom after shooting at the toilet door, then noticed Ms Steenkamp was not in bed.
Mr Pistorius said he then realised she could have been in the toilet.
5. Toilet door
Mr Pistorius said he went back to the bathroom but the toilet was locked, so he returned to the bedroom, pulled on his prosthetic legs, turned on the lights before bashing in the toilet door with a cricket bat.
Forensics expert Johannes Vermeulen told the court that the height of the marks on the door caused by the cricket bat suggest Mr Pistorius was on his stumps at the time.
6. Emergency calls
Mr Pistorius’s defence team say he then called security at the gated housing complex and a private paramedic service before carrying Ms Steenkamp downstairs.
A security guard claimed it was the other way round, and he had called Mr Pistorius first after reports of gunfire. However, phone records shown to the court revealed Mr Pistorius called the estate manager at 3:19am, a minute later he called the ambulance service and at 3:21am he called estate security.
A minute later he received an incoming call – estate security calling him back.
According to police phone expert Francois Moller, Mr Pistorius called his friend Justin Divaris a short time later and just after 4:00am he called his brother Carl.