A mentally ill Stillwater man stabbed his father several times from behind while his sister fought to stop the fatal attack, according to criminal charges filed in Washington County District Court.

William James Scheel, 31, was charged Monday with intentional second-degree murder in connection with Friday’s alleged assault on his father, William Mark Scheel, 59.

The elder Scheel died from “significant stab wounds in the back of his neck” after the attack at the family residence on Mulberry Street, according to the complaint filed by Assistant County Attorney Siv Yurichuk.

The defendant was taken to Regions Hospital in St. Paul with stab wounds inflicted by his sister, who used a knife herself in trying to stop the attack on their father.

Police arriving at the scene found the sister in the front yard, yelling for help, and their mother kneeling and praying inside, saying of her husband, “Please don’t let him die.”

The younger Scheel was under civil commitment for schizophrenia and living in a group home. He had been ordered to receive medication by injection, but recently was allowed to administer his own medication even though the family knew he had a history of not taking it, the complaint said.

“The defendant had had several psychotic breaks in the past and had threatened to kill his father on previous occasions, claiming his father was involved in Black Magic and needed to be killed,” the complaint said.

According to the charges:

The younger Scheel came to the family home for dinner on Friday, with his mother planning to order takeout food. As his sister and their father sat on the couch, waiting for the food, the defendant allegedly began stabbing his father from behind.

Unable to pull the defendant away, his sister ran to the kitchen for a knife. She then began stabbing her brother, trying to save the elder Scheel. Their mother also tried to stop the attack.

When police arrived they found father and son on the floor, covered in blood.

Police interviewed the younger Scheel’s girlfriend and another resident at the group home.

“It was confirmed the defendant had not been taking his meds the last few months and that he was declining and becoming psychotic,” the charges said.

The defendant, in an interview with Stillwater police Sgt. Jeff Stender, admitted his intention to kill his father, the charges said.

Scheel was being held in secure custody at Regions until doctors approve his transfer to the Washington County jail. His initial court appearance hasn’t been scheduled.

In an obituary, William Mark Scheel was remembered as a talented musician, songwriter, artist and poet. Services will be held at 4 p.m. Saturday at the Bradshaw Celebration of Life Center, 2800 Curve Crest Blvd., Stillwater, with visitation starting at 2 p.m.