Pietermaritzburg - An 18-year jail sentence - three more than the prescribed minimum - was on Tuesday imposed on a Durban police sergeant who shot dead a young mother because she refused to accompany him to his home.The heavily built Sergeant Selby Hlongwa, 43, was convicted by the High Court in Pietermaritzburg on Friday of shooting dead Princess Ngcobo as she left work. Princess, who used to live with him until she found that he was paying lobola for another woman, was shot in the head at close range with his service pistol in Florida Road, Durban, in January 2012.He became angry when she refused to go home with him, and he shot her.He tried to create a scenario saying she was shot by two passers-by.Judge Mohini Moodley said his crime was made worse by his neglect of his duty to protect her constitutional right to life. The HIV-positive Hlongwa, who has nine children from different sexual relations, was roasted by Moodley.Fathering nine children showed that he had sex without using a condom, said the judge. This showed that he had disdain for the rights of his partners and their children to be free of infection.'Mercy has to be deserved'Murdering the young Princess deprived her 2-year-old son of her love and support.Her murder placed an additional burden on her family who were already struggling financially.Moodley said that violence by police officers against their partners was distressingly frequent and severe.Domestic violence in South Africa was among the highest in the world and offenders should be shown no tolerance.While presiding officers often show some mercy in sentencing, mercy had to be deserved, she said.Hlongwa had shown no remorse or apologised to Princess's family. Mitigating factors advanced for him were that he was a first offender and that the murder was not planned or premeditated. However the aggravating factors far outweighed them, Moodley said.As a trained and experienced policeman he must have realised that shooting her in the head would be fatal, the judge said.