The BBC has seen a copy of Zuma-Sambudla’s affidavit, which is unsigned but was widely reported in local media.
“I was not a recruiter, agent, operator or facilitator of any unlawful activity,” she says.
The BBC has also seen a statement Zuma-Mncube gave police, alleging that her half-sister – along with two men, whom she named – lured 17 South Africans to Russia “under false pretences” and were “handed to a Russian mercenary group to fight in the Ukraine war without their knowledge or consent”.
“Among these 17 men, who are requesting the South African government for assistance, are eight of my family members,” Zuma-Mncube says in the statement.
In her affidavit, Zuma-Sambudla reveals that she herself had received non-combat training in Russia, and it was arranged by a man whom, she says, she did not know until he contacted her.
When he suggested recruiting more people to take part in what she believed would be a similar programme, she “shared [this] information innocently” with others, including family members, she says in the affidavit.
“I would not, under any circumstances, knowingly expose my own family or any other person to harm,” the MP adds in the affidavit.
The discovery that people had been tricked into joining the war had “caused me profound shock and distress”, she says.
“I am myself a victim of deception, misrepresentation, and manipulation,” Zuma-Sambudla adds in the affidavit.
Earlier this month, the South African government confirmed it had received distress calls from 17 of its citizens trapped in Donbas after being lured to join mercenary forces on the promise of lucrative contracts.
One of the voice notes the BBC heard says that 24 South Africans had originally been duped into going to Ukraine, but three of them were taken back to Russia as they were deemed to be medically unfit.
Another voice note says one of the South Africans who was forced to stay in Ukraine was wounded, possibly by shrapnel and his whereabouts are unknown.
A report by financial news agency Bloomberg said some men had also been recruited from neighbouring Botswana.
South Africa’s government has remained tight-lipped on the situation since its statement earlier this month. It had promised to work through “diplomatic channels” to bring them back home, but this has not yet happened.
With his brother still trapped in a war zone, Xolani speaks of his family’s anguish.
“We can go five days without hearing from him because he’s off doing military stuff. The family is concerned about his life,” he says.
In the meantime in voice-note exchanges with his family, Sipho keeps repeating the appeal: “It’s tough here… we all [just] want to come home.”