Detective Senior Sergeant Manus Walsh said Ms Cooper’s remains were discovered near the Albany Highway in Ashendon.
“Forensic staff are currently processing a gravesite in which female remains have been located,” he said.
“We believe the remains to be those of Julie Ann Cooper, 55 years of age, from Doubleview.”
Ms Cooper had not been seen or heard from since August 17.
A 31-year-old man, who police say knew Ms Cooper, is in police custody and assisting with their inquiries.