Former Blue Bulls' rugby player Phindile Joseph Ntshongwana appeared to be possessed by satan, the Durban High Court heard on Wednesday.
A woman allegedly kidnapped and raped by Ntshongwana said he had acted as if there was an animal or satan inside him.
Ntshongwana is charged with the murder of Thembelenkosini Cebekhulu in Montclair on 20 March 2011, Paulos Hlongwa two days later, Simon Ngidi the following day, and an unidentified man sometime that week.
All were hacked to death with an axe.
He is also accused of kidnapping and raping a woman on 28 November 2010, and assault with intent to do grievous bodily harm. He also faces two charges of attempted murder.
He has pleaded not guilty.
The woman, who cannot be named, was kidnapped in central Durban and was held captive for three days.
She said Ntshongwana's mood changed from normal to violent and angry during their time together.
"He was angry, as if he wanted to fight. The manner in which he was acting was as if he wanted to finish up with me, kill me," the woman said.
During cross-examination, Ntshongwana's attorney Themba Mjoli told the woman she had lied when she told the court he had smeared Danone yoghurt on his body and private parts and had told her to lick it off.
"The whole story about the Danone is in your imagination and an after-thought," he said.
Mjoli said the woman had not mentioned the incident in her statement.
The woman said when she gave her statement she was still in shock and feared for her life.
Ntshongwana had not carried a weapon, she said.
She had not screamed for help when they were at Ntshongwana's home or tried to get the attention of petrol attendants when they went to a service station.
Mjoli asked her why she had not screamed when a man knocked on the door of Ntshongwana's room.
"I was scared. He showed me he would kill me," she said.
She said Ntshongwana spoke to her as if he knew her, but did not give her a name.
Mjoli put it to the woman that when Ntshongwana was saying that she had aborted his child, and killed it by infecting it with HIV/Aids, it was all in his imagination.
He said Ntshongwana was oblivious to the events relayed to the court.
Mjoli said Ntshongwana had been mentally ill.
Ntshongwana has been diagnosed with bipolar disorder and schizophrenia.
He raped the woman three times.
The woman said she had received counselling for a week when she was admitted to hospital.
She sobbed during the cross-examination.
The trial continues.