Cape Town - Celebrated Afrikaans author Winnie Rust was helping Nigel Plaatjies attain his dream of becoming a policeman.Instead, while she was planning his future, he was plotting her murder, her daughter testified in the Western Cape High Court on Monday."She chose to invest herself in Nigel and he chose to kill her," Helena Reid said during sentencing proceedings for the 19-year-old, who was once a promising athlete.Rust had been paying for Nigel's sports activities and school fees since Grade 7 and he was a regular visitor to her home.Nigel and his uncle Johannes Plaatjies were convicted in December of robbing and murdering Rust in her home in Uitsig, Wellington on May 11, 2016.Read: Two found guilty of robbing, killing writer Winnie RustJudge Elize Steyn found that the two accused had acted together when they committed the crime, despite Nigel's claim that he was forced by his co-accused, who is his mother's brother and who has a string of convictions to his name.A family photo was presented to the court, which also features Nigel and his sister, who were considered part of the family. His mother, Lien, had worked for Rust's daughter as well as Rust's home.'The mastermind behind the murder'On the day of her murder, Rust's husband Dr Manie Rust, found her body on the kitchen floor when he awoke to the sound of the bell ringing at 15:30.She had injuries to her face and had been strangled. Her hands and feet were bound.Reid said, when she saw what Nigel and his uncle had bought with the stolen money - items such as takkies, a music system and an iron – she questioned why he would swop her mother's valuable involvement in his life for "a few thousand rand and bags of worthless goods".He was a familiar face in their home, and regularly had lunch with Rust before she helped him with his homework. Also read: 'She was my biggest fan' - Winnie Rust murder accused"While you slyly in the shadows planned her death, she was planning your bright future. Everywhere in her office we found notes where she reminded herself about your urgent needs and milestones in your life."When this court case started, we hoped that you were the vulnerable … youth that was influenced by your criminal uncle. But, during the course of the trial, it became clear that you were the mastermind behind the murder and that you involved your uncle to execute your own dark plan."The happy home in Third Avenue, where my [siblings] and I grew up and where my father lived for almost 50 years, where so many irreplaceable childhood memories were created, changed overnight into a damned murder [scene] – a place of unscrupulous betrayal and suffering," she said.Nigel showed no remorse and, in the two years since Rust's murder, he never asked her family to forgive him, Reid testified."Our family gave you the best and in return, you do the unthinkable to us. In vain we look for signs of humanity in your behaviour, signs that you are heartbroken about the motherly figure, the mentor that you killed in such a cruel way.Also read: Winnie Rust, 77, may have tried to fight off killer – pathologist"Never do you speak the truth about my mother's last moments – what her final words were, about the cruel realisation in her eyes when she realised with shock that the young man in who she invested so much, betrayed her."Rust's friend, Eugenie Wiggins, also testified about the author's involvement in the Wellington community and the local museum."She was our first lady," Wiggins said.Former Wellington mayor Herman Bailey also spoke of Rust with fondness, saying she had done much to bridge the divide between the coloured and white residents that apartheid had created.He described her as the town's icon and said that locals had been devastated by her "senseless death".Proceedings continue on Tuesday.