To a big development in the case of the utah doctor convicted of killing his wife in the bathtub of their home. Just days before sentencing his lawyers claim a key witness lied on the stand. They now... See More
To a big development in the case of the utah doctor convicted of killing his wife in the bathtub of their home. Just days before sentencing his lawyers claim a key witness lied on the stand. They now want a new trial. Abc's aditi roy has the story. Reporter: Martin macneill seemed disheveled as he appeared in court monday on a charge unrelated to his november conviction for killing his wife, michelle. Really struggling, it's very difficult for him to be convicted of something that he feels completely maintains his innocence for. Reporter: Now with macneill's sentencing just days away a possible hail mary. His lawyers asking the judge to dismiss the case or grant him a new trial on the basis that a key witness may have lied on the stand. That witness, a federal inmate WHO testified MacNeill confessed to him about the murder. Did he ever describe or did you of ask him about why he -- yes. -- Killed his wife? He said she was in the way, that she wanted the house and his. Reporter: The inmate also told jurors he did not have a deal with prosecutors to testify. I didn't ask him for anything. I didn't ask him for any kind of deal. Nothing like that. Reporter: But macneill's defense attorneys say they have new evidence from phone calls and e-mails that contradict that testimony. In his phone calls, he references the deal. Reporter: Macneill's defense also points out that inmate was released from prison after his testimony, ahead of his expected 2016 release date. Overnight prosecutors telling abc news they are confident the verdict will stand. While the judge considers the MOTION, MacNEILL'S LAWYER ALEXIS Who testified against him -- I was concerned that my father killed her. Reporter: -- Says she hopes her father spends the rest of his life in prison. We thought this was over and I'm just hoping that my father can take responsibility for his action and stop hurting his family. Reporter: For "good morning america," aditi roy, abc news, san francisco.
This transcript has been automatically generated and may not be 100% accurate.