Lewis Jenkins gave up his chances of a post-conviction appeal when he pleaded guilty in Jones County to killing Teressa Gillum, the state Court of Appeals has ruled.

The Appeals Court on Tuesday upheld a Jones County judge’s dismissal in 2006 of Jenkins’ post-conviction petition. Inmates use post-conviction petitions to argue that they have found some new evidence that might win them a new trial.

In 2004, Jenkins was sentenced to 20 years in prison with five years suspended after pleading guilty to manslaughter in the slaying of Gillum.

Gillum was killed and remained missing for months. Her badly decomposed body was found in a shallow grave by hunters Feb. 8, 2001, near a graveyard south of Ellisville. Authorities said the woman was killed the previous November or December.

Prosecutors said Jenkins, of Ellisville, told investigators that he and Gillum struggled and when the woman came at him, Jenkins said he hit her in the head with a blunt object.

On appeal, Jenkins argued he had some newly discovered evidence and would not have pleaded guilty if he had known about it. The Appeals Court ruling did not specify what the new evidence was.

Appeals Judge T. Kenneth Griffis, writing Tuesday for the court, said it didn’t matter what evidence Jenkins claimed to have.

“When a defendant pleads guilty, he is admitting that he committed the offense. Therefore, by definition, a plea of guilty negates any notion that there is some undiscovered evidence which could prove his innocence,” Griffis said.

The Appeals Court also rejected Jenkins’ claim that he didn’t know what he was doing when he pleaded guilty.

Griffis said court records show the trial judge repeatedly questioned Jenkins about his plea and the advice he received from his lawyers before accepting the guilty plea.