A mentally ill man has allegedly confessed to beheading his mother with a metre-long sword after having a family breakfast. Matthew Skalitzky, 40, from Sun Prairie, Wisconsin, is accused of murdering mother Jane, 68, at his home on Friday, 18 September, before telling police "she's not my real mother", PIX11 News reported.

Skalitzky had stayed overnight with Jane and his father Joseph, sharing breakfast with them before his mother had agreed to drive him home, according to police. Upon arriving at his townhouse, which he shared with another man, Skalitzky is reported to have gone upstairs to his room with Jane before launching the vicious attack.

The roommate told police that when the pair arrived on Friday morning Jane had been in good spirits, "being friendly and greeting him". However, Skalitzky had seemed "distant and unemotional" before the pair went upstairs, according to Madison Newspapers.

After around 15 minutes of the pair being upstairs, the roommate heard a loud stamping noises coming through the floor. As he climbed the stairs, the roommate heard Jane screaming "no, no, no" before opening the door to Skalitzky's room and finding her headless body on the floor with wounds to her hands, according to PIX11 News.

The witness said that Skalitzky handed him the sword and he walked him downstairs to a couch "like a child" before going outside to call the police. When police arrived they found the bloody sword on the porch and Skalitzky coming down the stairs from his room. According to ABC 27 News, when he was asked if his mother was dead, he allegedly replied: "Yes, but she's not my real mother."

Skalitzky's father told police his son had stopped taking his prescription medication after reading about negative side effects. However, he had started taking them again a few days before his mother's death. Local news media have reported that Skalitzky was suffering from a mental illness, but the condition was not identified.

According to the State Journal, Jane retired after a 30-year career as a special education teacher in the Sun Prairie School District. Skalitzky is being held in a secure mental health facility, police said. WKOW reported that police officers seized marijuana, a sword, a machete, a gun, a journal, and medication in searches of Matthew Skalitzky's home, car, and Jane and Joseph Skalitzky's home.