The judge did not immediately issue a decision on Scott Curley's competency, following a two-day hearing in Flagstaff.
The prosecution and defense agree that Curley is mentally ill. They disagree over whether he can rationally and sufficiently help prepare his defense.
Curley, 25 of Fredonia, Arizona, faces a premeditated first-degree murder charge in the August 26, 2010 death of Kane County, Utah, Sheriff's Deputy Brian Harris. The 41-year old law enforcement officer was tracking Curley, who was wanted for burglary when he was ambushed, according to authorities. Curley fled on foot into the wilderness along the Arizona-Utah border following the shooting. He was captured east of Kanab, Utah, after a massive four-day manhunt.
Curley has said he understands insanity is his best defense.
Prosecutors say Curley's consistency in statements over time and knowledge of court proceedings prove he can aid his lawyer.
But the defense says its work with Curley is hampered by his intent on proving psychotic beliefs.