James Michael Wiley, the Thermo-polis teenager accused of shooting to death his stepmother and three younger brothers last year, pleaded guilty Monday and was sentenced to life in prison.

James Michael Wiley, 16, entered his new pleas in Douglas before 8th District Judge William Taylor. The youth had originally pleaded innocent by reason of mental defect or disease to four counts of first-degree murder and arson. But Monday he changed his plea to guilty on three counts of first-degree murder, one count of second-degree murder and arson.Taylor sentenced him to three life sentences and one 20-year-to-life sentence to run concurrently, plus 18 to 20 years for arson.

Wyoming Public Defender Leonard Munker said Monday night that the defense simply didn't have the evidence to support the innocent plea - especially since all the psychologists, psychiatrists and counselors who examined him found him sane.

Wiley admitted to the Nov. 24, 1990, murders of his stepmother, Becky Wiley, 34; his brother, Jesse Lee Wiley, 13; stepbrother Willy Lee Brady, 10; and half-brother Tyrone Wiley, 5.

After shooting each of them, he said, he set the family's mobile home ablaze.

The murders occurred after the teenager returned home from wrestling practice and got into an argument with his stepmother. He then got a shotgun and methodically gunned down the four.

The boy's father, Mike Wiley, was guiding a duck hunting party down the nearby Big Horn River at the time of the shootings, saw smoke and returned to find his home engulfed in flames and his wife and three sons dead.