Convicted murderer Jon Evans Yount, attempting to obtain a jury trial on escape charges against him, has filed a brief with state superior court challenging a lower court decision that prohibits him from retracting an October guilty plea.

Yount, 50, pleaded guilty to escape charges Oct. 11 under the condition that Centre County District Attorney Ray Gricar drop additional conspiracy charges stemming from Yount's April 1986 flight from the State Correctional Institution at Rockview.

The plea agreement, Yount contends in the brief, stipulated that Gricar's office promised not to ask for the maximum seven-year sentence, but later did.

The escapee used these grounds to file a motion with Centre County President Judge Charles Brown Jr. alleging "prosecutional misconduct," and petitioning for a full trial by jury.

Brown denied the motion last month.

But Yount, whose 20-year string of appeals on his murder conviction eventually reached the U.S. Supreme Court, filed a brief with the state superior court on Dec. 20 contesting Brown's decision.

No date has been set for appeal review, said Yount's attorney, Centre County Assistant Public Defender Deborah Lux.

Yount, a former math teacher serving a life term for the 1966 murder of one of his high school students in Clearfield County, wandered away from an unsupervised work detail near Centre County's State Correctional Institution at Rockview on April 5, 1986.

Police charged Diane Brodbeck, 45, a married mother of two from Wellsville, with driving him from the scene.

Yount, who gained statewide notoriety during his trial in 1966, was again thrust into the spotlight when his escape was featured in May on "Unsolved Mysteries," a television program that dramatizes large-scale crimes.

A subsequent viewer's tip led federal authorities to the pair in June of this year. When apprehended, Yount was living under an alias in Coeur d'Alene, Idaho.

Brodbeck, who also presented an alias to authorities, was arrested 45 minutes later as she returned home from a part-time job. She pleaded guilty in December to conspiracy charges relating to the escape, and faces up to seven years in a state prison.

Her sentencing is scheduled for Jan. 23 in Brown's chambers.

Yount remains incarcerated at the State Correctional Institution at Huntingdon, a maximum-security prison about 30 miles from State College where he was transferred in September.