A man who killed his 15-month-old baby and his wife's grandparents was sentenced to three life terms in prison, the National Prosecuting Authority said on Wednesday.The 40-year-old Ketso Peter Ntaje was sentenced in the Gauteng High Court in Johannesburg on Tuesday, NPA regional spokesperson Phindi Mjonondwane said.Ntaje was also sentenced to 15 years for the attempted murder of his wife, Matshidiso Ntaje. The sentences will run concurrently. He pleaded guilty to the offences, Mjonondwane said.Matshidiso had begged the court not to set him free. "The couple was experiencing marital problems that led to Matshidiso leaving their matrimonial home to live with her grandparents in Kagiso [west of Johannesburg]," said Mjonondwane.According to Mjonondwane, the court heard how Ntaje arrived on the night of April 24, 2019, and found the grandparents in the main house with the toddler and fired several shots at close range, killing them on the spot. "He then proceeded to the backyard rooms occupied by his wife and fired more shots through the locked door and windows. "Fortunately, Matshidiso escaped unharmed after she heard gun shots and locked herself inside her room," Mjonondwane said. Ketso eventually handed himself over to the police. She said Matshidiso had testified during aggravation of sentence arguments that she had locked herself inside her room after hearing her grandfather saying: "No Ketso, don't do it!".His plea was then followed by several gunshots, she said. Mjonondwane said prosecutor Nonkululeko Serepo argued that pleading guilty did not imply automatic leniency.Serepo asked the court to consider the prevalence of such cases, the brutality and disregard for the right to life, and the outcry for tougher action against perpetrators of violent crimes on women and children.