This is according to a psychiatrist at Weskoppies and part of the forensic team who assessed her in 2015 shortly after her arrest.
A magistrate referred her for a 30-day evaluation to ascertain her mental status at the time she killed her children.
Dr Jacobeth Pooe, who was a member of the panel of three psychiatrists who assessed Matjane, on Wednesday took the stand in the Gauteng High Court, Pretoria, to shed more light on why the panel found that Matjane could be held criminally responsible for her actions.
The mother is accused of killing the two boys in April 2015, after fetching them from school and driving from Pretoria east to a remote spot in Hammanskraal, where she shot them at point-blank range.
The mother’s defence is that while she did not deny pulling the trigger, she could not remember anything about the actual killings.
Psychiatrist Dr Ivanov Savov this week testified on her behalf and said she could not be held responsible for her actions due to the side-effects of the medication she had taken for a few days leading to the incident and on the day of the killings.
He diagnosed her as suffering from sane automatism.
But Pooe said from her assessment there was nothing to make her believe the woman had suffered from a mental defect which resulted in her killing Alvero, 2, and Keyondre, 6, on April 17, 2015.
The expert said that on that day Matjane acted normally; she fetched her children from school, strapped them into the car and drove normally until she found a remote spot.
The next thing she claimed she remembered was “waking-up” and finding her sons dead, one in a pool of blood outside and the other in the front seat of the car.
Matjane told Pooe that she had felt suicidal earlier in the day and fetched her husband’s firearm from the safe. She went to the garage to shoot herself, but decided against it. Instead of taking it back to the safe, she placed it in the boot of her car.
Pooe said if she did not want to use the gun, one would expect her to put it back in the safe. “It seems to me this was planned,” she said.
Matjane also told her that she had been feeling depressed for two days before the incident. This increased on the day when she returned from taking the children to school and her husband, psychiatrist Dr Maxwell Matjane, was not home for breakfast with her as usual.
She phoned him and he said he was at a building supply shop. Matjane also said she had a disagreement with her husband about the bathroom of the new house they were building.
“He told her ‘I will build you this house but leave you with the children’ She did not like what he said, as she interpreted that as meaning he would leave her. She told me that he did not mean what he said and that she had a friend in her husband.”
Pooe also referred to the fact that after the killings Matjane went to a nearby house to get help, where she asked a woman she found there to phone her mother and her husband. She even supplied their numbers.
She testified that Matjane told her she took medication on the days leading to the incident as well as on the day.
According to her, the last medication she took was at 7am that day.
Pooe said that after she had shot the children she took all the medication in her possession at that time.
Her advocate Piet Pistorius told Judge Hans Fabricius that his client was concerned that he (the judge) did not treat the defence as fairly as he did the prosecution. He accused the judge of “snapping” at the defence from time to time.
The judge asked the prosecutor whether it was her impression that he was “rude to her colleague”.
Prosecutor Elbie Lennard denied this. Pistorius said “the record will speak for itself” and the judge responded “I agree it will speak for itself.”
The case is proceeding.