A judge in Virginia Beach yesterday sentenced a man convicted of murdering his 13-year-old adopted son to 41 years in prison, rejecting the defendant's plea that he has learned to be a better father.

Circuit Judge Edward W. Hanson Jr. said he found no reason to overturn a jury's recommendation that Michael Diehl serve 20 years for first-degree murder, 10 years each for abduction and felony child neglect, and 12 months for misdemeanor assault.

Diehl, 42, and his wife, Karen Diehl, 36, were convicted by separate juries in July in the death of Dominick J. (Andrew) Diehl last Oct. 29. The emotionally disturbed boy was tied naked to the floor of the family's school bus in which the family lived, beaten with a stick and forced to consume his excrement and urine. An autopsy showed he died from repeated blows to the head.

Karen Diehl, who is free on bond, will be sentenced Sept. 16 on a jury's recommendation that she serve 31 years for involuntary manslaughter, abduction, felony child neglect and misdemeanor assault. She wept in the back of the courtroom as her husband was sentenced.

Diehl told the judge that he regretted his son's death and would be a better father to his remaining 16 children if he were freed.