A 31-year-old Bucks County man diagnosed with schizophrenia has pleaded guilty to fatally stabbing and cutting the throat of his 52-year-old mother in their Lower Makefield Township home in 2016.

In a hearing Monday in Bucks County Common Pleas Court in Doylestown, Judge Raymond F. McHugh accepted Zachary  Cope's negotiated plea of guilty but mentally ill and said he would likely accept the recommended sentence of 10 to 40 years.

Cope has told investigators and doctors that he believed his mother, Rebecca Cope, was an assassin posing as his mother and had been hired to kill him. He told police he attacked her in December 2016 because she told him to rub olive oil on a new cutting board — something, he said, his real mother would never ask him to do.

After killing his mother, Cope fled their home on Lower Hilltop Road  to Taylorsville Road several blocks away. Police found him standing in a driveway wearing only underwear, a small blanket, and one flip-flop in 40-degree weather. Police found his mother in a pool of blood on her kitchen floor. She had been stabbed more than 70 times.

Cope's sentencing is set for March 26. He is expected to receive a mental-health evaluation with recommendations made for treatment he could receive while incarcerated.