PORTLAND — A trial is due to get under way for a Maine man charged with strangling his girlfriend then cutting off her head and setting her body on fire.

There’s no question that 29-year-old Chad Gurney killed 18-year-old Zoe Sarnacki in his apartment on May 25, 2009.

The issue that will be decided at what is expected to be a two-week trial beginning Monday in Portland is whether Gurney was sane.

Gurney once told a friend he believed he was a prophet. He is using an insanity defense.

Prosecutors maintain that the former Liberty University student and lacrosse standout was fully aware of what he was doing and the wrongfulness of his actions.

Gurney’s case is being decided by a judge after he waived his right to a jury trial.