WILLIAMSON COUNTY, Texas (KXAN) - A Williamson County man sentenced to 42 years in prison for the 1991 murder of his wife has gotten his conviction reversed by the Third Court of Appeals. In June 2014, a jury found Rex Nisbett, 55, guilty in the cold case murder of his wife Vicki, despite the fact investigators never found his wife's body.

An appeal from the judgment of conviction filed on Dec. 15 says, "Having reviewed the record and the parties' arguments, the Court holds that there was reversible error in the trial court's judgment of conviction. Therefore, the Court reverses the trial court's judgment of conviction and renders a judgment of acquittal. Appellant is discharged from all further liability for the offense of murder as charged in the indictment." The state will not be allowed to retry the case.

Nisbett's defense team says, "The case should never have been prosecuted. Rex Nisbett is innocent and District Attorney Jana Duty should never have brought these charges against him with the thin circumstantial evidence." The defense team is currently working on the logistics on when Rex would be released from TDCJ prison. He is currently imprisoned at the Coffield prison, southeast of Dallas. His original projected release date was March 2055.

Nisbett and his wife were high school sweethearts who married right after high school. In 1991, while the couple was in the process of getting divorced, Vicki moved out and into an apartment with their three sons. However, later that year, Vicki agreed to let him stay at her apartment during the holiday season. Friends testified that Vicki continued to see other men and that it led to more problems for the couple.

On Dec. 14, 1991, Vicki went missing.

During the initial investigation, Nisbett became a suspect. Over the years, previous district attorneys did not prosecute him because Vicki's body was never found. Without a body, the case was considered too thin and circumstantial to prove beyond a reasonable doubt. The case remained open, and the investigation continued on and off over the years until Williamson County District Attorney Jana Duty reopened the case file, he was indicted on Vicki's murder on March 21, 2013.

In June of 2014 - more than two decades after Vicki's disappearance - Nisbett's trial began.

During opening statements, Duty told the jury a close friend of Vicki's would testify about hearing a "commotion" during a phone call on the night of the disappearance. Another neighbor testified saying Rex asked for him to watch the three boys while he borrowed the neighbor's truck, only to return the truck with damage to the trunk area.

The jury ultimately found Nisbett guilty of murder and sentenced him to 42 years in prison.

In the court's ruling, it states even if Vicki is in fact dead, "the evidence remains insufficient to support appellant's conviction for murder."

Jana Duty's Handling of Cases

This is not the first major case mishap for Williamson County District Attorney Jana Duty. She has only tried two felony cases in her career, Rex Nisbett's case and the capital murder case against Crispin Harmel. Harmel's case ended in a mistrial in 2014 because the defense was not able to access video in the case. A year later, a judge determined Duty intentionally withheld evidence in the case.

As a result, the State Bar of Texas publicly sanctioned Duty for withholding the evidence and violating a gag order in the same case. Duty agreed to an 18-month fully probated suspension of her law license, meaning she can still practice law as long as she doesn't violate the law or any rules of professional misconduct during the probationary period.

Duty only has 15 days left in office before newly elected District Attorney Shawn Dick takes over the helm in Williamson County.