Private investigator Chris Saunders is on the stand in the North West High Court in Mmabatho, on day two of the Stella murder trial. 

He is being cross-examined by Xander Bylsma's advocate, Niven Rai, according to Netwerk24. 

Bylsma previously pleaded not guilty to murdering Sharnelle Hough, 17, and Marna Engelbrecht, 16, in the early hours of Saturday, May 26, in the girls' hostel of Hoërskool Stella in the North West. He allegedly strangled the girls and tried to make their deaths look like suicide.

In a recording played in court on Tuesday, Bylsma can be heard saying: "And then I hanged her."

When proceedings got underway on Wednesday, the second part of the recording was played.

Saunders was heard asking Bylsma if he thought that Sharnelle didn't want to live anymore. The accused responds: "Yes."

When Saunders asks if is that why she didn't scream, Bylsma once again responds with a "yes". 

The private investigator then asks Bylsma why he then murdered Sharnelle's friend. Bylsma's response to this was inaudible. 

The conversation between Saunders and Bylsma took place shortly after the girls' bodies were discovered, and Saunders spoke to him for a long time to find out how the two had died. 

During proceedings, Rai asked Saunders why he had gone to Bylsma's parent's farm, instead of allowing the police to do their job. 

Saunders responded that he had spoken to the police and told them he was going there after he had received information that Bylsma had previously tried to cause trouble at the hostel. 

YOU reported that a reliable source had said the content of the sound recording didn't bode well for Bylsma.

"It's the end of smooth sailing for me," his mother Mercia told the publication. "From here on it's going to be a rough ride. But my boy is positive."

On Tuesday, Dr Tromp Els, a forensic pathologist who conducted the autopsies on Shannelle and Marna, detailed their injuries, reported Netwerk24. 

"Shannelle’s body showed throttling signs. She also displayed defence type injuries in the fingers. The back of her eyelids had blood due to pressure on the neck, and blood from the nose as a result of an injury on the nose," Dr Els told the court. 

He also said that she had injuries on the nails of her left and right hands, as if she had tried to scratch her attacker, or tried to pull the green nylon rope from her throat. 

Bylsma's lawyer recused himself from the case last Thursday at the start of the trial.