Julie Dixon murdered her fiancé David Twigg by locking him in a storeroom at the couple's workshop in Burgh le Marsh, Lincolnshire, and setting fire to the building.The court said her performance in front of emergency service workers was worthy of an Oscar before being jailed for 23 years.The 43-year-old then dialled 999, telling them that they had been attacked by two masked intruders who were responsible for the killing.She changed her story on the second day of her trial, however, when she first said his death was the result of a failed joint suicide pact and then saying it was an assisted suicide.Mr Twigg died as a result of the fire which was started on March 13 last year. Judge Heath told Dixon that he rejected her story, branding it a pack of lies.He said: 'Her performance in the 999 call and to the emergency crews at the scene, including to the firefighters and at the hospital would have been worthy of the highest praise had she been an actress in some fictional drama and would have warranted an Oscar nomination.'He added: 'I am sure that this was not an assisted suicide. I am sure it was a premeditated killing. David Twigg did not want to die.'Judge Heath called Dixon an 'unreliable and incredible witness' and said he was sure from evidence that she bought the petrol which was used to set fire to the premises, that she struck the match which started the blaze and left Mr Twigg to die, and that she planted keys on a neighbour's land and mentioned to others a dispute with them in order to try to place suspicion elsewhere.The court heard that Dixon and Mr Twigg, who had been in a relationship since 1996, ran the bespoke joinery business together - Mr Twigg handled the practical side of it while Dixon was responsible for all administration and financial duties.Using funds from her divorce settlement and family input, Dixon purchased the land in Burgh le Marsh in 1997 but the business struggled and Mr Twigg was eventually declared bankrupt in October 2010.The court heard that he owed Her Majesty's Revenue and Customs £37,500. Dixon did her utmost to conceal from Mr Twigg the debts that were being amassed and went so far as to tell officials who wanted to talk to him about his financial situation that he was ill or working abroad.Judge Heath said: 'She was resourceful and imaginative in her dealings with the insolvency service.'The court heard evidence that Dixon had mentioned to friends that she was unhappy in her relationship with Mr Twigg.There were also internet searches on the couple's computer carried out in December 2010 under the username 'Julie' looking for: 'The thing that kills you and does not show on a post-mortem' and 'How can I disguise tablets in food?'Another one searched for an answer to the query: 'I've tried to disguise tablets in chocolate syrup but it still does not work.'The court heard that chocolate syrup was ordered online and signed for by Dixon upon its delivery.Dixon, who stood in the dock with her hands clasped and her head bowed as she was sentenced, claimed that the reason she made up the masked intruder story was because Mr Twigg did not want anyone to know he had committed suicide, but she felt she eventually had to tell the truth.Judge Heath said: 'She told me that the reason was because she could not carry on with the way it was because it was not fair to the family, and she could not put them through it.'How hollow those words sounded when they were uttered. 'How hypocritical they were.'Short excerpts from victim impact statements from Mr Twigg's parents, who were in court for Dixon's sentence, were read to the court.His mother, Janice Twigg, said: 'David was all Roy and I had. 'Not being able to see him or speak and talk with him and tell him how we love him is very hard to accept.'Roy Twigg said: 'I can't say anything more, only losing David has created a vast void that I'm struggling to fill.'Detective Chief Inspector Stuart Gibbon, of Lincolnshire Police, said: 'This has been a complicated investigation, made more difficult by the actions of Julie Dixon who lied from the outset, misleading the emergency services and raising fears within the community of Burgh Le Marsh by reporting fabricated events. 'Even now, she has failed to admit her full involvement in the death of David Twigg and we may never know the full circumstances of why she carried out the actions she did.'David was a hard-working, respected member of the community whose life was cut short in a brutal way and I hope his family and friends are able to take some comfort from the outcome of the court case.'I would like to thank everyone who has assisted with the inquiry and who all worked so tirelessly to see justice served.