Wounds to Reeva Steenkamp's head and right arm would have caused arterial spurting and a trail of blood in Oscar Pistorius's house after he shot her, the High Court in Pretoria heard on Wednesday.

"The volume of blood in the head would have been a good source for the constant dripping blood down the stairwell," said blood spatter analyst Colonel Ian van der Nest.

The other main source of blood would have been her right arm, which ballistics expert Captain Chris Mangena testified earlier was hit when she was in a defensive position.

Van der Nest said, according to analysis of the toilet seat, that the blood found there should be in keeping with a "significant event" near the toilet and "the head coming in contact with the toilet seat".

"The deceased sustained a wound to the head in the surrounds of the toilet area," he said.

Steenkamp's mother June returned from the tea break to see the images of her daughter's blood on a screen next to her in court.

A woman from the ANC Woman's League hugged her tight as she sat down.

Pistorius sat with his head down after huddling with his lawyers during the tea break.

Van der Nest said he found other debris on the inside of the toilet lid.

"It could be brain, it could be skin matter," he said.

The paralympic athlete has been charged with the premeditated murder of Steenkamp and contravening the Firearms Control Act.

He allegedly fired a shot from a Glock pistol under a table at a Johannesburg restaurant in January 2013.

On September 30, 2012 he allegedly shot through the open sunroof of a car with his 9mm pistol while driving with friends in Modderfontein.

He has pleaded not guilty.

He said he thought there was an intruder in the house when he fired into the toilet, realising only afterwards it was Steenkamp.