A soldier dressed as The Joker was shot dead by police on Sunday in Shenandoah National Park in Virginia after he reportedly pointed a loaded shotgun at them.

An affidavit filed Wednesday by the FBI identifies the man as Army Spc. Christopher Lanum, 25, a suspect in the attempted murder of another soldier at Fort Eustis earlier that day.

According to authorities, Lanum -- dressed in The Joker makeup and costume he'd worn for Halloween -- and girlfriend Patsy Ann Marie Montowski attacked Launum's barracks suite mate Spc. Mitchell Stone, who was shocked repeatedly with a stun gun and then slashed in the throat with a knife.

Montowski told the FBI her boyfriend idolized The Joker.

Stone was taken to a hospital for serious injuries and later released.

Lanum and Montowski fled the scene in a minivan, which a park ranger later spotted some 200 miles from the Army base. The ranger called for help, and Lanum led police on a low-speed chase that ended when Lanum drove over a spike strip and crashed.

The affidavit states Lanum pointed a shotgun toward police, and refused commands to lower his weapon. A trooper fired through the window of the driver's side of the minivan, and Lanum's shotgun discharged. Police then opened fire, killing Lanum.

Montowski also was shot, and was treated for "non-life threatening wounds." She was arrested late Wednesday and charged as an accessory after the fact to assault.