Engineer raped and murdered partner, 37, weeks after she warned police he was controlling and could 'flip' at any time, court hears

By CLAIRE DUFFIN, SENIOR REPORTER Published: 14:20, 11 June 2026 | Updated: 14:26, 11 June 2026 A boyfriend raped and murdered his partner less than three weeks after she warned police he was 'controlling' and could 'flip' at any time, a court heard today. Marine engineering worker Stephen Sexton, 38, strangled Joanna Derkacz, 37, a recruitment consultant, after their relationship broke down, jurors were told. Prosecutors allege Sexton, a father of one, fractured her neck with his forearm or the crook of his elbow after subjecting her to 12 months of 'controlling and coercive' behaviour. A court was told Sexton was on police's radar as less than three weeks before Miss Derkacz's death she warned officers he was 'evil'. Miss Derkacz told police Sexton was 'narcissistic', that 'he doesn't like it when I go out', and said 'he's got this thing where he flips'. There were 'red flags' that were missed by police and officers did not realise 'how far Sexton might go', prosecutors said. Portsmouth Crown Court, Hants, also heard that Sexton has a previous conviction for assaulting his ex-wife and 'had a history of assaulting his previous partners'. Sexton denies murder, rape, and two counts of coercive or controlling behaviour. Miss Derkacz was found dead at their home in Waterlooville, Hants, on December 28, 2023. She had fractures on both sides of her neck.  Stephen Sexton, 38, is accused of strangling Joanna Derkacz, 37, after their relationship broke down Miss Derkacz was found dead at their home in Waterlooville, Hants, on December 28, 2023 Sexton denies murder, rape, and two counts of coercive or controlling behaviour The court heard the couple had been in a relationship for three years and they rented a flat together with their two dogs, Bella and Teddy.  But Sexton's behaviour declined when he lost his job and started taking drugs.  The prosecution said the relationship became 'controlling and coercive' and on occasion 'violent and threatening'.  Jurors were told that by December 2023 Sexton's behaviour had frightened Miss Derkacz and she had told her sister he had tried to strangle her but that she had managed to push him away. He also took her phone more than once and broke a phone and her laptop in fits of anger, jurors were told.  On another occaion he locked her out because she had arrived home 20 minutes late following a night out with friends.  Nicola Shannon KC, prosecuting, said: 'Over the months it had involved jealousy, paranoia and attempts to control and isolate her.' Ms Shannon said that after he locked her out, he reported her missing to police 'no doubt hoping that they would find her for him'. 'The episode backfired, however, because it acted as the trigger for her asking him to move out and for her telling the police about the breaking of her laptop and his abusive behaviour,' she said.  'He didn't move out immediately - their dogs had just had a litter of puppies and it was agreed that he could stay until they were sold, but they lived in separate bedrooms.' On December 11, two police officers went to see Miss Derkacz as part of a 'welfare visit'. She told the police that he was 'very controlling' and 'narcissistic' and 'he doesn't like it when I go out'. She added that 'he's got this thing where he flips'. She told the police that his behaviour is 'tormenting' and that he is 'evil', saying that 'I don't think he is bipolar but when he flips he cannot stop'. Miss Derkacz denied to the police that Sexton attempted to strangle her. Ms Shannon KC said: 'Joanna herself seems to have made what we say proved, tragically, a fatal mistake, in underestimating him. 'It is one of the tragedies of this case, you may think, that although Joanna was wary, and there were, in retrospect, so many 'red flags', neither she, nor the officers, seem to have realised how far Stephen Sexton might go when he realised she was slipping from his grasp. 'Her optimism and compassion may, we say, have cost her her life.' Sexton has a son from his previous marriage to Tara Sexton and has a criminal record for an attack on her. Ms Shannon KC said: 'You will hear evidence of Sexton having convictions for assaulting Tara Sexton and for damaging her mobile telephone.  'Sexton had a history of assaulting his previous partners.' It was heard Miss Derkacz's body was found by her sister, Arleta, who was concerned because she couldn't reach her. Arleta went to her sister's address on the way back from the airport on December 28 as she was not answering her phone - which she considered unusual. When she arrived the door was unlocked and the dogs were running around - 'seemingly agitated'. Sexton appeared at the top of the stairs looking 'really scared' and denied that Miss Derkacz was there saying she was 'out with friends'. Arleta said she was going upstairs to see her and pushed him away and ran upstairs where she saw her sister 'lying on the bed, lifeless. She saw her skin was grey'. She ran downstairs and started shouting 'You killed my sister, you killed my sister'. Ms Shannon KC said: 'By this time Stephen Sexton, was standing in the kitchen, holding a knife. 'When she first saw him with the knife he was staring at her. He said 'you're not leaving'. 'She said it felt like she was 'in a movie' - it felt unreal but at the same time she was petrified and froze. 'She told police that for a moment he was acting like he didn't know what to do. 'Then she saw him turn it on himself and point it into his wrist. She realised that was her opportunity to get out and she ran.' It was heard Arleta was screaming 'like an animal' and the police were called. Sorry we are not currently accepting comments on this article.