EVERETT — Nearly two years later, an Arlington man has admitted in open court to killing his sister.

David Thorsen, 52, was arrested in June 2013 after a Snohomish County sheriff’s sergeant discovered the body of Karen Harris, 53, under a blanket in a field near their parents’ former Arlington home.

Thorsen on May 7 pleaded guilty to domestic violence second-degree murder in Superior Court.

Harris died of blunt-force injuries. In paperwork accompanying his plea, Thorsen said he was attempting to assault his older sister, and she died as a result. Sentencing was set for June 11.

Thorsen faces 12 to 18 years in prison under state sentencing guidelines.

Police believe Thorsen hauled his sister’s body out to the field with a riding lawnmower.

Detectives found blood in the house and on the mower. They also discovered blood-spattered clothes. The plaid shirt and shorts appeared to be the same clothes that Thorsen was seen wearing a few days before in business surveillance footage, court papers say.

The defendant had been living at his parents’ home. They had recently died.

The death of Karen Harris came to the attention of police after her son reported her missing. He went to his grandparents’ house and found his uncle extremely drunk. He returned a couple of hours later and found his mother’s car parked on the property behind an outbuilding.

The son also told police that he saw his uncle a few hours later riding on the lawnmower with a long tow strap attached.

Police came to the property to investigate the missing person report. Thorsen apparently was attempting to end his own life by breathing exhaust fumes from his car when a sheriff’s deputy approached him, court papers say.

Neighbors reported hearing a loud argument between a man and a woman the day before Harris’ body was discovered.