A Kitsap County man was charged Wednesday with raping and murdering his older sister, according to the Kitsap County Prosecuting Attorney’s Office.

Michael A. Battersby, 51, was arrested Tuesday night at the Seabeck-area home he shared with his 61-year-old sister, where she was found dead over the weekend.

Sheriff’s deputies were called at about 6:30 p.m. Sunday to a home in the 16900 block of Northwest Indian Ridge Drive in the Seabeck area of unincorporated Kitsap County, where they found Battersby attempting CPR on the unresponsive woman, according to charging documents. She was pronounced dead at the scene, according to the sheriff’s office.

Deputies initially believed the death was from natural causes and called the county coroner, but then they walked into the woman’s bedroom to look for her medications and noticed an instant message conversation on the woman’s computer screen in which she said her brother had raped her the night before and she had bruises all over, prosecutors allege.

An autopsy performed Tuesday by the Kitsap County Coroner’s Office determined she had been strangled, asphyxiated and drowned, and had a blunt-force injury to the back of her head and injuries consistent with forcible sexual contact, according to court documents.

Battersby told detectives he and his sister had been drinking Saturday night and “playing patty cake at ‘full force,'” often missing each other’s hands and bruising each other’s arms, according to the document of probable cause that lays out the state’s case against a suspect. He also said his sister was so intoxicated she lost consciousness and he had to drag her along the carpet to her room, six inches at a time, according to prosecutors.

Battersby is charged with first-degree domestic violence murder and second-degree domestic violence rape. He is being held at the Kitsap County Jail in lieu of $1 million bail.