DOYLESTOWN, Pa. (AP) - A man diagnosed with schizophrenia has been sentenced to 10 to 40 years in the murder of his mother in their Bucks County home.

Thirty-two-year-old Zachary Cope pleaded guilty but mentally ill in January to third-degree murder and possession of an instrument of crime.

Man Charged After Allegedly Telling Passerby He Killed His Mother 

Authorities in Bucks County said he stabbed 52-year-old Rebecca Cope in December 2016 in the Lower Makefield Township home, then flagged down a motorist to tell him about the crime.

The Doylestown Intelligencer reports that authorities said the defendant said he stabbed his mother during an argument about putting olive oil on a cutting board and believed she had "morphed" into an FBI agent "or vice-versa."

Man Pleads Guilty But Mentally Ill In Murder Of Mother

Officials said at Monday's sentencing that Cope will be credited for time served since his December 2016 arrest.

Copyright 2018 The Associated Press.