A judge refused Friday to dismiss a case against a Vista man charged with murdering a married San Diego Wild Animal Park co-worker, 10News reported. Denise Vasseur, 33, disappeared last Sept. 22. Her body has not been found. Attorneys for Patrick Hamilton (pictured, left), 44, asked a judge to set aside testimony from a preliminary hearing in February that resulted in the defendant being ordered to face trial for murder, according to 10News. Prosecutors had not proven that the victim was dead, or if she was that it was due to foul play, the lawyers argued. At most, the attorneys argued, Hamilton should be tried for manslaughter. But Superior Court Judge John Einhorn rejected the argument, saying that the prosecution had a low burden of proof requirement at that stage of the legal process. "The burden is not as strict as it would be on them at trial," Einhorn said. The judge cited "ample evidence" from the transcripts that the woman was dead and that Hamilton was responsible for it. Despite the "apparent love of her job," the judge said, Vasseur (pictured, right) has not returned to work or contacted her employers. She has not communicated with her husband, family members or professors at a university where she was about to receive a master's degree, he said. Vasseur had not taken any clothes or belongings with her and had abandoned two dogs she was very fond of, Einhorn said. And her credit and charge cards have not been used, he said. Hamilton apparently had an affair with the woman in the summer of 2000, but she was back with her husband by September, the judge said. Whether Vasseur was trying to break off her relationship with the defendant, or intended to "egg him along" while she remained married is circumstantial evidence of motive for Hamilton to kill her, Einhorn said. "The behavior of Mr. Hamilton before, during and after the 22nd (of September) raises an appearance of suspicion," he said. Hamilton called the Wild Animal Park that morning to report that he and Vasseur were having car problems and wouldn't be in, Einhorn said, but neither one ever showed up for work. By Sept. 27, Hamilton was spotted in Gilroy, Calif., where he fled from authorities, then jumped out of his moving vehicle, Einhorn said. Trial is set for Sept. 24.