MacNeill, 58, was scheduled to be sentenced Monday afternoon, but the hearing was delayed after prosecutors asked for more time to respond to a motion to dismiss filed earlier this month by MacNeill's defense attorney, Randall Spencer.
The motion argues that Spencer was unable to effectively cross-examine victim Alexis Somers during trial because police inadvertently lost her recorded police interview from 2007.
Spencer said Monday that the hearing was rescheduled for Sept. 15. He told reporters that MacNeill's conviction should be thrown out because without that recorded interview which he called the "most critical piece of information" in the case he couldn't effectively cross-examine Somers at trial.
Prosecutor David Sturgill left the courthouse Monday without commenting to reporters.
In early July, a jury found the former doctor guilty of second-degree felony forcible sexual abuse, finding that he inappropriately touched his adult daughter. He faces up to 15 years in prison for the crime. The Tribune normally does not identify sexual abuse victims, but Somers has publicly proclaimed herself MacNeill's victim.
A different Utah County jury convicted MacNeill last year of murdering his wife by drugging her and drowning her in a bathtub at their Pleasant Grove home.
The sexual abuse occurred May 23, 2007, about five weeks after the death of MacNeill's wife, 50-year-old Michele MacNeill.
Somers testified at trial that she was sleeping on her parents' bed alone, when she woke to find Martin MacNeill rubbing her buttocks, and licking and kissing one of her hands. She said her father told her, "Oh, oh, I'm sorry, I'm sorry. I thought you were your mother."
Before the July sex-abuse trial, Spencer filed a motion to dismiss, asking for the case to be tossed because of loss of evidence. But Judge Samuel McVey denied the motion, saying that while there was some negligence in deleting Somers' interview, it was not "gross negligence" and it was not done in "bad faith."
Spencer claims that without the recorded interview, MacNeill was denied the opportunity to cross-examine Somers about inconsistent statements "with her own words" rather than the words in the detective's case file.
Meanwhile, MacNeill has yet to be sentenced in the murder case. Spencer filed a similar motion in the homicide case, asking for murder and obstruction of justice charges to be dismissed or that MacNeill be granted a new trial.
Fourth District Judge Derek Pullan is expected to have a ruling on the within the next few weeks. A sentencing date for the murder case will then be set, if Pullan does not grant a new trial.
Spencer argued in the motion that MacNeill should get a new trial because a federal inmate lied on the stand about a possible early release he received in exchange for his testimony and that prosecutors did not disclose that a deal was in the works.
Prosecutors chalked up claims of a "secret deal" to a "conspiracy theory," and said no such deal had been planned.
The federal inmate testified during MacNeill's four-week trial that the defendant confessed to him that he drugged his wife, then drowned her in a bathtub at their Pleasant Grove home April 11, 2007.
Prosecutors said MacNeill killed his wife so he could continue an affair with another woman, Gypsy Willis.