Johannesburg – Sandile Mantsoe, the man accused of murdering his girlfriend Karabo Mokoena, claims prison warders beat him up at Johannesburg Prison two weeks ago.Mantsoe's lawyer, Victor Simelane, made the claim in the South Gauteng High Court in Johannesburg on Monday."My client was severely assaulted and I am having a hard time with police investigating it," Simelane said.He alleged that the incident took place on March 5.Judge Colleen Collis said the Department of Correctional Services would look into the alleged assault.The 27-year-old accused last appeared in court in September last year.He has been charged with the premeditated murder of Mokoena, who was killed on April 28, 2017. Mantsoe has also reportedly been charged with assault with the intent to do grievous bodily harm, for allegedly assaulting Mokoena on March 27, 2017.The matter was postponed to April 16, after State advocate Pakanyiswa Marasela told the court that new evidence had come to light on March 15.READ: 'New developments' lead to postponement of Karabo Mokoena murder trialSince the expert who needed to go through the evidence was in Durban, Marasela requested a postponement. Simelane said he had only been informed of the new evidence on Monday morning. "I need every piece of evidence. I can't properly represent my client until I have all the evidence," he added.Missing evidenceAccording to Judge Collis, two pieces of evidence were still outstanding. One was expected to be received on Monday afternoon.Mokoena's charred remains were discovered in an open veld in Lyndhurst, Johannesburg after her family and friends launched a search operation when she went missing.They searched for her at Mantsoe's Sandton apartment, but it is alleged that he told them that he had not seen her since they broke up in April.Mantsoe, a married father of three, was reportedly in a romantic relationship with Mokoena since October 2016. It is believed that he and his wife were estranged.The accused has denied killing Mokoena but, during his bail application, said he disposed of her body after he came home and found that she had committed suicide.CCTV footage from Mantsoe's apartment allegedly showed that they had been together on the night Mokoena went missing.The trial is set to run for three weeks when it begins in April.