Grunewald described Steyn as a master manipulator who had made those close to her believe that she was dying and was in constant need of medical care.
Cecilia had made numerous claims including that she was a satanist and was the bride of Satan, the court heard.
The court heard that Cecilia had claimed to have supernatural powers including the ability to walk on water, turning into a wolf and makings things disappear and reappear.
Cecilia, according to Grunewald and her former best friend Candice Rijavic, had told them that she could see when a person was pure or if they had demons.
After 52 witnesses, state closes case against 'Krugersdorp killers'
The state has closed its case in the matter involving three people accused of 11 murders in Krugersdorp.
Cecilia Steyn, Marcel Steyn and former insurance broker Zak Valentine are standing trial in the South Gauteng High Court for their alleged involvement in the murder of 11 people between 2012 to 2016. The trio have pleaded not guilty.
Three other people - including Marcel’s mother, Marinda Steyn - are serving lengthy jail terms in connection with the killing spree.
The matter was postponed to Thursday to allow the defence to consult the accused.
The initial killings were allegedly sparked by a split in a church group called Overcomers Through Christ (OTC). The group’s stated aim was converting satanists to Christianity. Cecilia and her friends formed the Electus Per Deus (Chosen by God) group after the split.
The first victims were linked to the OTC church: Natacha Burger, 33, and her neighbour Joyce Boonzaaier‚ 68‚ who had their throats slit in Centurion in July 2012. The next month 75-year-old pastor Reginald Bendixen was stabbed and hacked to death with an axe at his home in Honeydew.
Prosecutor Gerrit Roberts SC closed the state's case on Monday after calling his last witness, police captain Xolile Jongani.
Jongani, the court heard, worked at the victim identification centre in Pretoria when he was sent to Bloemfontein in 2015 to collect samples from the remains of a deceased person. "I was sent to Bloemfontein to assist with an identification of an unknown body," Jongani said.
He said he attended a postmortem in Bloemfontein, after which he was given three samples which he took for DNA analysis. The samples included a tooth and vertebrae.
During cross-examination, Jongani was grilled on why he had made it look like he had collected the DNA samples from the body himself.
"I made a mistake. I did not collect the samples from the deceased. Dr Liebenberg conducted the postmortem and he gave me the samples," he said.
Jongani explained that his job at the time was similar to that of a courier service as they transported samples from mortuaries to the laboratory.
The state called 52 witnesses, some of whom were friends of the accused or had interacted with them. Others were relatives of the victims.
One of the key state witnesses, Ria Grunewald, who was a leader of OTC when Cecilia Steyn was also part of the group, told the court how Steyn had manipulated her and other members of the group.
Grunewald told the court that she and Steyn were extremely close and she treated her like her daughter.
Grunewald described Steyn as a master manipulator who had made those close to her believe that she was dying and was in constant need of medical care.
Cecilia had made numerous claims including that she was a satanist and was the bride of Satan, the court heard.
The court heard that Cecilia had claimed to have supernatural powers including the ability to walk on water, turning into a wolf and makings things disappear and reappear.
Cecilia, according to Grunewald and her former best friend Candice Rijavic, had told them that she could see when a person was pure or if they had demons.
During the trial, the court also heard that the accused had killed a homeless man to fake Valentine's death.
Le Roux Steyn, who is serving a 35-year jail sentence for his role in the murders, told the court that they orchestrated a plan to fake Valentine's death to claim his life policy.
"The plan was to find someone who looked like Zak‚ the same size and built like him‚ then kill him and wait for the policy to pay out‚" Le Roux had told the court.