Tyler Lyon, the Castle Rock man accused of beating his father into a coma two years ago, was sentenced Monday to fourth-degree assault that became known as the chainsaw case.

Authorities accused Tyler Lyon, 30, of hitting his then 61-year-old father, Kevin Lyon, early in the morning on Aug. 1, 2014. He got about nine months in jail, much more than the prosecution had asked for.

According to court documents, Tyler Lyon’s mother, Deborah Lyon, had thrown his car keys in a patch of ivy to prevent him from driving drunk. He started up a chainsaw to trim the ivy back and retrieve the keys. His father Kevin Lyon went outside to talk to him about it, and the next thing Deborah Lyon and her daughter heard was Tyler Lyon called for help for his father.

Deborah Lyon and her daughter found Kevin Lyon unconscious and lying with the back of his head on the edge of the driveway. He was driven to St. John Medical Center and then immediately airlifted to a Portland Hospital, where doctors discovered three fractures, on his nose, around his right eye and on his skull.

He was in a coma for a month and his short-term memory was damaged.

Police suspected Tyler Lyon hit his father with either his fists or chainsaw based on blood spatter evidence that suggested in part that Kevin Lyon was upright when he sustained his injuries. Police said Tyler Lyon gave conflicting accounts of what happened and denied hitting his father. He had two prior assault convictions, one for assaulting his mother.

He was originally charged with second-degree domestic violence assault.

Debbie Lyon told authorities her husband has balance problems and had taken a sleeping pill and that she believed her son didn’t assault her husband.

Tyler Lyon Monday took an Alford plea, meaning he didn’t admit guilt but acknowledged that prosecutors may have enough evidence to convict him. While the prosecutor recommended only 10 days in jail, Superior Court Judge Gary Bashor sentenced him to 274 days in jail and a year on probation.

Contact Daily News reporter Lauren Kronebusch at 360-577-2532.