Authorities say he told a witness that "when you see Bev Perdue with a .38 caliber slug in her head, I did it."
An arrest warrant also shows that the 30-year-old said, "Call the law and I'll take care of them too."
McDermott is a native of England, but lives in Youngsville. He's currently in the Wake County Jail on $150,000 bond.
McDermott is also supposed to appear in court next month on an involuntary manslaughter charge.