AUBURN, Ala. -- The man accused of killing an Auburn University student from Marietta was indicted Wednesday on charges of capital murder and his attorney has filed documents to prepare an insanity defense.

Courtney Lockhart, 23, was also indicted on a charge of robbing a business in his Smiths Station hometown, District Attorney Nick Abbett said.

Lauren Burk, an 18-year-old freshman, died March 4 after she was found lying on a highway suffering from a gunshot wound. Her car was later found burning in a parking lot on campus.

Lockhart was arrested in Phenix City, Ala., three days later, after leading police on a short car and foot chase.

Authorities said he told police he kidnapped Burk from the Auburn campus, then robbed her and forced her to remove her clothes before shooting her.

He said he then drove her car back to the campus and set it on fire, according to police.

Lockhart's attorney, Joel Collins, did not immediately return a call seeking comment. But he has said that he is preparing an insanity defense, filing court papers claiming Lockhart has a mental disease and "lacks the ability to understand the difference between right and wrong."

District Court Judge Russell Bush has ordered an evaluation of Lockhart by a state psychiatrist or psychologist before setting a trial date. He also issued a gag order covering parties in the case.