UPDATE 1/3/13
LOUISVILLE, Ky. (AP) -- A man who killed three of his classmates at a Kentucky high school in 1997 has lost his bid to withdraw a guilty plea after a federal appeals court concluded he could have acted sooner to seek a new trial.

The U.S. 6th Circuit Court of Appeals in Cincinnati on Thursday ruled that 29-year-old Michael Carneal was competent as early as 2004 and could have challenged the plea then.

Carneal opened fire at a school prayer meeting in Paducah, killing 17-year-old Jessica James, 15-year-old Kayce Steger and 14-year-old Nicole Hadley. Five others were wounded.

The attorney for 29-year-old convicted shooter Michael Carneal argued Wednesday before the panel in Cincinnati that his client's appeal was timely and should be allowed to proceed.

Corneal has schizophrenia and is arguing that he wasn't mentally competent to plead guilty to the shooting at the time, when he was 15.

The Kentucky Attorney General's Office countered by saying that Corneal filed the appeal too late and that his conviction and life sentence should stand.

The panel is now considering the matter but may not issue an opinion for months.

The U.S. 6th Circuit Court of Appeals in Cincinnati will consider whether 29-year-old Michael Adam Carneal waited too long to try and withdraw his guilty plea to killing three classmates and wounding five in 1997.

A federal judge in Paducah ruled in August 2011 that Carneal could have moved sooner to pull back the guilty plea in the 1998 attack on classmates at Heath High School near Paducah.

Carneal is serving life in prison with a chance at parole after 25 years.

Carneal's attorneys say he wasn't mentally competent to plead guilty or withdraw the plea within the proscribed time limits.