TERRE HAUTE, Ind. — An Indiana man has pleaded guilty to abducting his two young sons at knifepoint and killing one of them just days after his wife told him she wanted a divorce.

Katron Walker pleaded guilty to murder and attempted murder as part of an agreement entered in court Monday in Terre Haute.

Prosecutors dropped their request for the death penalty, and a judge accepted his pleas and scheduled a sentencing hearing to begin Aug. 18. Walker, who has waived his right to appeal his sentence, could face 45 to 100 years in prison under the terms of his plea agreement.

Prosecutors said the boys' mother approved of the plea agreement.

Walker was convicted Monday of fatally stabbing 4-year-old Collin Walker in June 2006 after grabbing the boy and his brother at knifepoint from the backyard of their grandfather's Terre Haute home.

He was also convicted of attempted murder in the stabbing of his 2-year-old son, Monte Walker, who suffered neck and chest wounds.

Defense lawyer Jessie Cook said Walker's attorneys changed their plan to mount an insanity defense after determining that going to trial posed too great a risk that Walker would be sentenced to death or life in prison without parole.

She planned to argue for the minimum sentence due to mitigating factors, chiefly that Walker suffers from mental illness.

Cook said one main reason Walker decided to plead guilty was to spare his ex-wife the ordeal of a trial.

The boys, who were the subject of an Amber Alert, were taken after their mother, Teresa Walker, told her husband she wanted a divorce and had moved into a shelter with her sons.

Police found the van Walker used in the abduction near a private lake south of Terre Haute.

While dogs were searching the area, Walker ran from an abandoned trailer and jumped into the water, dragging his naked children with him, police said.

Officers jumped in after them and grabbed Monte Walker, but they could not find his brother in the murky, dark lake. A dive team found Collin Walker's body the next day in about 12 feet of water. His throat was cut and he had puncture wounds to his chest, police said.

Katron Walker, who had marijuana and methamphetamine in his system at the time of his arrest, was treated for wounds that police said were self-inflicted.

Vigo County court records show Walker was convicted of methamphetamine possession in early 2003 and sentenced to probation.