Robert McWhir was "annoyed" and "agitated" on the night Marissa Aldrich died, Cambridge crown court has heard. McWhir, 26, of Potton Road, St Neots, who denies the murder of Ms Aldrich on December 22 last year, was upset because Ms Aldrich, who he had an "on-off" relationship with, had been seeing another man. On the third day of the trial, Clare Oakley, the partner of Luke Holder, gave her evidence. Mr Holder and Ms Oakley, held a pre-Christmas drinks party at their flat in Cambridge Street, St Neots, on December 21. Mr Holder's mother, Tracey Underwood, was staying at the flat and McWhir arrived during the early part of the evening, but Ms Aldrich came later. Ms Oakley told the court she had known McWhir for about five years but was "never that fond of him". She said before Ms Aldrich arrived McWhir spoke to her on the phone. "They were arguing. The phone was on loud speaker, and Marissa was telling him how she didn't want to have to choose between McWhir and her ex-boyfriend." She told the court she heard McWhir tell Ms Aldrich 'I aint nobody's second best'. Ms Oakley said: "After that, Luke told him to just invite her over as it was Christmas and we should all just have a good time." Later that evening, McWhir and Mr Holder went to the Tesco Express store on Love's Farm to meet Ms Aldrich and buy some lager. Ms Oakley then told the court that Ms Aldrich had told her that McWhir had held a knife to her throat previously, because he believed she and her ex boyfriend may steal money from him. Ms Oakley said: "I told him that he was out of order and a d**k head for doing it." She said after that the pair seemed fine and Ms Aldrich was sitting on McWhir's lap for most of the evening. She then told the court she decided to go upstairs to spend time with her neighbours. She was upstairs for about two hours, when Mr Holder came upstairs. "Luke came upstairs to tell me that he [McWhir] had left his tobacco pouch at ours. I told Luke to give him a call and tell Marissa and Bobby to come back and have a few more drinks." The court then heard how Mr Holder called McWhir and heard him say 'I am killing her, I'm killing her'. Ms Oakley said: "Luke's face changed suddenly and he just passed me the phone. He started running downstairs, and I was confused. I asked Bobby 'what's up' and he just said 'I am killing her'. He said it so calmly. When I asked him why he said, 'I've had enough of her talking to other blokes'. "I could hear Marissa in the background groaning. It sounded like she was dead already. She used her last breath of air to try and communicate with me. I could tell she was dead." The court then heard how McWhir asked Ms Oakley to tell Luke to come to the wooden bridge. Ms Oakley then heard shouting and screaming and said it was Luke and he was saying 'he's done it, it's too late'." Ms Oakley then ran to the bridge to look for Ms Aldrich and managed to flag down a passing car after recognising the driver as Ben Cornwell. In his testimony, Mr Cornwell told the court how he helped Tracey Underwood drag Ms Aldrich out of the water. Mr Cornwell said: "Clare was in a state. I had no idea what she was saying, but she kept mentioning a dead body so I went to help her." He then told the court how he and Ms Oakley searched for Ms Aldrich's body but it was "very dark". He said: "I saw a coat, and what I thought was two gloves attached to it. Then when I adjusted I realised it was two hands. I couldn't see her face, but her nose was sticking out of the water. "As soon as I saw her I thought she was dead. Her face was white, which is probably why I thought her hands were gloves. "At this time, Tracey ran over and we both went straight down to get her. I told Clare to call an ambulance as she was obviously someone she cared about and I didn't want her to be any more upset. "Tracey got in the water to try and drag her out, but it was too hard. We managed to scoop up her body and we dragged up to the top of the slope. By that time I could see blue flashing lights and the paramedics were there." The trial continues on Thursday.