A sibling of two sisters who allegedly murdered their mother for her life insurance pay-out says she never expected her own relatives to commit such an evil act.Sara van Rooyen* (not her real name), the two women's half-sister, spoke to News24 about the ordeal on Friday, saying her sisters "had the spirit of revenge".READ | Two Barberton sisters allegedly kill their own mother for R80K life insurance payoutMpumalanga police launched an investigation into the murder, in which the two daughters allegedly killed their 62-year-old mother to cash in on her life insurance. According to police spokesperson Brigadier Leonard Hlathi, the younger sister allegedly invited her mother for a visit, News24 previously reported. "Information indicates that [the younger sister] organised her 41-year-old boyfriend as well as two other male friends and then waited for her mother to arrive. When [the mother] eventually arrived... she was allegedly kidnapped, assaulted, senselessly gang-raped by the two male friends while [the younger sister] and her friend were holding her," Hlathi said.Life insurance policyShe was then allegedly strangled and her body dumped by the side of the road in Barberton.The Sowetan reported that police claimed one of the women held their mother down while she was being raped.It later surfaced that a friend of one of the sisters allegedly took out a life insurance policy in the mother's name valued at R40 000. Should she have suffered an unnatural death, the policy would pay out double. Speaking to News24, Van Rooyen said: "It is so sad that we live among people who we call our sisters, our brothers or close family friends, and you don't know that you are sitting right next to them and there's a price [on] your head."My mother was a dead person walking," van Rooyen said. She and her sisters shared the same mother, but they never had a close relationship. This was because the two women's behaviour was unbecoming, Van Rooyen said. "When this incident happened, my sister came to me as if she wanted to reconcile."Only to find there was more to that, because we didn't know what she was planning or what she was plotting," Van Rooyen said."They thought, in this world, they don’t need anyone to the extent that they never used to speak to anyone on my mother’s side; they lived their own lives," she said. Describing her beloved mother, Van Rooyen said she was a strong, fit woman, adding that she had thought she'd have many more years to spend with her parent. "She was a happy person. Just the other day I told her that she would live until she is 90 or 100, because her body size was small, she never used to take any medication, and she was fit too - she could walk 20km without getting tired."While she never thought anyone could do such an "evil" thing to their own family, Van Rooyen said her sisters had "the spirit of revenge"."[They think] my mom was never there for them, but they can't say that because how can my mom raise myself [and my little brother] and not raise them? "They had that pride, most of the time they wanted to exclude themselves and make themselves special or something," she said. "When I discovered that my mum passed on, I knew [my sister] was involved."She said this was because the two had allegedly tried to poison their mother earlier this month with what seemed to be paint thinners. While the daughters will soon face trial, the family has taken a serious blow."My brother and I are now officially orphans. He is hurt and angry. I keep on praying for him, I talk to him and I calm him down," Van Rooyen said, adding that she is now the mother of the house. Both sisters are now remanded in custody until their trial continues next month, but Van Rooyen said she hopes they are never released. "I feel like a life sentence is nothing… I hope they give them years, like 100 or 200 years, because I know then they will die inside prison."They decided to play God, but God must punish them harshly," Van Rooyen said.*News24 has opted to use a pseudonym to conceal the identity of the woman quoted as reveal her identity would potentially identify her sisters. As the suspects are linked to a case involving a sex crime they cannot legally be named until they plead.