South African Olympic athlete Oscar Pistorius has told his murder trial he was "heartbroken" when he saw the body of his girlfriend Reeva Steenkamp.

"I crouched down over her... and I checked to see if she was breathing or if she had a pulse," he said.

The prosecution has now finished five days of gruelling cross-examination, which has seen the athlete break down on several occasions.

Mr Pistorius denies murder, saying he mistook his girlfriend for an intruder.

The prosecution says he deliberately shot dead Ms Steenkamp after the couple had had an argument and has suggested he is staging his emotional outbursts.

He faces 25 years to life in prison if convicted of premeditated murder.

Before his cross-examination ended, the court was shown a photograph of the toilet covered in blood where Ms Steenkamp was shot in February 2013.

Mr Pistorius, 27, said that after shooting through the toilet door at what he thought were intruders, he realised he may have mistakenly killed his girlfriend, a 29-year-old model and law graduate.

He said he tried to break down the door with his shoulder, before using a cricket bat, all the time screaming in panic.

But the double-amputee sprinter said he stopped screaming when he finally opened the door and saw the body.

When asked why, he replied, his voice trembling with emotion: "I was heartbroken... overcome with sadness."

Prosecutor Gerrie Nel said the athlete had deliberately killed his girlfriend following an argument.

"You fired four shots through the door whilst knowing that she was standing behind the door. She was locked into the bathroom and you armed yourself with the sole purpose of shooting and killing her," he said.

Mr Pistorius replied: "That is not true."

The athlete has previously said he and Ms Steenkamp had spent a quiet evening together before he woke up on hearing a noise in the bathroom.

After the cross-examination ended, Mr Pistorius' defence lawyer Barry Roux asked a few further questions before presenting to the court the Valentine's card which Ms Steenkamp had got the athlete.

The front of the card reads: "Roses are red, violets are blue..."

Inside, she had written: "I think today is a good day to tell you that, I love you."

Ms Steenkamp was shot dead in the early hours of Valentine's Day 2013 - before they had opened each other's cards and gifts.

Oscar Pistorius did not get to open the card on Valentine's Day

The court has been shown the toilet door through which Mr Pistorius shot Ms Steenkamp

Mr Pistorius has now ended his testimony.

The defence called forensic expert Roger Dixon as its next witness.

He told the court that with the light out, the room would have been almost completely dark, despite a couple of LED lights.

This supports Mr Pistorius' evidence.

The court also heard sound recordings Mr Dixon had made - of a cricket bat striking a door similar to that in Mr Pistorius' toilet, and another of gunshots fired through same door.

Mr Dixon seemed to struggle to tell the sounds apart, which the BBC's Pumza Fihlani in Pretoria says the defence will use to cast doubt on what neighbours say they heard that night.

Prosecution witnesses have testified to hearing a woman scream followed by gun shots, but the defence disputes their testimony, saying the only scream came from Mr Pistorius - after he had fired.

Judge Thokozile Masipa temporarily halted proceedings on two occasions on Monday after Mr Pistorius broke down sobbing.

Mr Nel suggested the Olympic sprinter was doing this on purpose when he was unable to answer the prosecutor's questions.

Both prosecution and defence have asked Judge Masipa to postpone the case until 5 May.

Mr Nel said members of his team were engaged in "more pressing" cases, which needed their attention, as well as "personal arrangements" over the Easter holidays.

The defence said the case should still finish on 16 May, as planned. The judge said she would deliver her judgement on this request on Wednesday.

If Mr Pistorius is acquitted of murder, the court must consider an alternative charge of culpable homicide, for which he could receive about 15 years in prison.

He also faces charges of illegally firing a gun in public and of illegally possessing ammunition, both of which he denies.

There are no juries at trials in South Africa, and his fate will be decided by the judge, assisted by two assessors.

Mr Pistorius is known as the "Blade Runner" because of the carbon-fibre prosthetics he uses on the track.