FAYETTEVILLE, N.C. — FBI documents released Thursday reveal disturbing details about a fatal shooting at a Fayetteville Veterans Affair hospital.

Arthur Charland Jr. was arrested Monday after allegedly killing Linda Leviton, a former coworker at the VA hospital's pharmacy.

According to an FBI affidavit, Charland confessed to killing Leviton, who he described as his "off-and-on girlfriend," after the two had a "bad" conversation the night of the slaying.

In his confession, Charland said he put his shotgun in a "shotgun box" and covered it in "Christmas wrapping paper" to make it look like a gift.

Documents also say that Charland went to the hospital, walked into the pharmacy and took out the weapon. He then told Leviton that she had "nerve calling me on the phone and trying to torture me again," before shooting her in the head and chest.

Charland, who turned himself in to VA police, told federal agents that he did an "awful thing to society" and that he was "sorry for doing this."

Charland is charged with first-degree murder and is scheduled to be in federal court in Raleigh on Monday. Leviton was the mother of two teenage children.