London ( CNN ) -- A jury in the case of two former personal assistants accused of defrauding celebrity chef Nigella Lawson and her ex-husband Charles Saatchi was sent out Thursday but has not yet reached a verdict . Francesca Grillo is accused of defrauding Lawson and Saatchi of 580,000 pounds ( $ 950,000 ) , and Elisabetta Grillo is accused of defrauding them of 105,000 pounds ( $ 172,000 ) . They deny the charges . The jury was sent home for the night and will resume deliberations Friday . One of the defendants was not in the dock at the end of deliberations Thursday because `` she is not feeling well , '' the judge said . The Italian sisters have told Isleworth Crown Court in west London that Lawson authorized their personal expenditures on Saatchi 's company credit cards , including on designer shoes , clothes and trips abroad . Their respective defense lawyers said in their closing arguments Thursday that the prosecution 's claims had not been proved . They also argued that for the jury to return a guilty verdict , it would have to be sure that Lawson did not authorize the sisters ' spending either explicitly or implicitly . Both defense lawyers questioned Lawson 's credibility as a witness and said their clients ' claims that she repeatedly used drugs were relevant to that issue . Elisabetta Grillo 's defense lawyer , Anthony Metzer , told the jury that his client was the `` soft underbelly '' by which Saatchi was attacking Lawson after the breakdown of their relationship . The couple divorced this year . Karina Arden , representing Francesca Grillo , said her client had made no attempt to hide her spending , so it was impossible for Lawson to say she was ignorant of it . The case has gripped UK media , thanks to revelations of drug use by Lawson and intimate insights into her troubled marriage to Saatchi , a millionaire art collector . Jane Carpenter , giving the prosecution 's closing argument in the case , said Thursday that the sisters had abused their position `` time and time again '' and that they `` grew bolder and greedier '' as time went by . `` Just because Saatchi is a wealthy man , obviously it does n't mean he should be defrauded by the staff , '' Carpenter said . `` That seems to be what the defense are putting forward . '' She urged the jury to find both sisters guilty . In her own testimony , Lawson confirmed she had taken cocaine half a dozen times , during two periods of her life , and used cannabis in the past . But she denied being a habitual user . The court heard that none of the witnesses had seen her take drugs . Lawson , whose culinary skills and flirtatious manner have long entranced UK audiences , has also appeared as a judge on the ABC show `` The Taste '' in the United States . A second season of the show is due to air in January .
NEW : The jury in the trial of Francesca and Nigella Lawson will continue deliberations January . The Italian sisters deny embezzling money from their former employers . At the trial , they alleged repeated drug use by celebrity chef Elisabetta Grillo . The prosecution says the sisters abused their position by buying luxury goods for themselves .