The Democratic Alliance (DA) on Sunday urged former Gauteng Health MEC Qedani Mahlangu to be contrite, truthful and take responsibility when she testifies at the Life Esidimeni arbitration hearings this week.
"Qedani Mahlangu should seek to make amends with honest testimony and a sincere apology to the relatives of the victims who have suffered so much from her ill-considered actions," said DA MPL Jack Bloom in a statement.
"She should acknowledge her personal and direct responsibility for this terrible tragedy rather than blaming officials as scapegoats."
Mahlangu is scheduled to appear at the hearings on Monday.
They are being held in Parktown, Johannesburg and are chaired by former deputy chief justice Dikgang Moseneke.
In 2015, Mahlangu was the MEC when the department decided to end a contract with Life Esidimeni and move mentally ill patients to a number of inadequate and some unlicensed facilities.
The death toll now stands at 143 mental health patients who died following this action. Many died of dehydration and hypothermia and some were allegedly raped. More than 50 patients are still missing.
"I hope that she avoids any more stalling tactics and testifies openly and truthfully without her previous arrogance that led to this tragedy," said Bloom.
He noted that officials who had already testified, had described a "climate of fear" that surrounded Mahlangu's decision to cancel the Esidemeni contract.
During previous testimony in December last year, then suspended - and now resigned - Gauteng health department head Barney Selebano said that he was scared to stand up to Mahlangu, after he continued acting in contravention of the rights of mentally ill patients under her instruction.
"It was tense," Selebano said at the time. "The culture of government is hard. The culture of hierarchy."
On Sunday, Bloom suggested that there were a number of key questions which Mahlangu had to answer.
These included what the "true reasons" for cancelling the contract were since a "study commissioned by the department found that it was cost-effective and provided good care".
She also needed to explain why she appeared to "ignore so persistently" warnings against the move of so many patients to often illegal and ill-equipped NGOs.
Bloom also said that Mahlangu's answers to questions he had previously put to the provincial legislature had been "untrue".
He gave the example of a written reply from November 2015, whereby Mahlangu apparently stipulated that 591 patients were placed with NGOs. Bloom said the figure was actually over 1000 patients who were moved.
Furthermore, Bloom said that it needed to be established during her testimony how much she had shared with the Gauteng premier and executive council as to what was happening at the time with the situation.
"What was their complicity in the decisions that were taken?," asked Bloom.
In November last year, Mahlangu issued a statement in which she denied that she had to be subpoenaed after allegations that she had refused to appear before the hearings.
At the time, Mahlangu's legal representative told the hearings that Mahlangu would only be available to testify in January when she was expected to finish a module for her Masters of business administration at the University of Bedfordshire in the UK.
Previously, the university said it had suspended Mahlangu over "the severity of the allegations" against her, but her legal representative told the hearings at the time that it had regarded the suspension as wrongful and unlawful and was planning to challenge it.