Botham Jean, Amber Guyger

A Dallas cop who shot an accountant in his own apartment says she fired at a “large silhouette” of a man she believed was an intruder in her darkened apartment. Amber Guyger was charged with manslaughter Sunday in the shooting death of Botham Shem Jean, 26, who was killed at his apartment door.

Guyger, 30, told investigators she was “tired” when she arrived home around 7:30 p.m. Central time after working a 15-hour shift. Guyger and Jean were neighbors at the upscale South Side Flats apartments located a few blocks from the Dallas Police Department.

Guyger parked her car on the wrong floor of the parking deck and walked to Jean’s apartment — which was one floor up from hers. Jean’s apartment was the only one on that floor with a red doormat.

When her key wouldn’t turn in the door lock, Jean opened the door.

According to the arrest affidavit obtained by PEOPLE, Guyger said she saw a “large silhouette” standing in the doorway of what she believed was her own apartment.

Guyger said the apartment was “nearly completely dark” inside when she unholstered her service weapon and fired twice, hitting Jean once in the upper torso.

She said she “gave verbal commands” to “the intruder” that he ignored, the affidavit states.

After the shooting, Guyger realized she was in the wrong apartment when she called 911.

Witnesses several doors down said they heard loud pounding and a cop yelling “Open up!”

But next door neighbor Alyssa Kinsey, whose apartment shares a wall with Jean’s apartment, told Heavy.com she did not hear any shouting or commotion in the hallway before the single gunshot rang out.

“These halls are echoey so I feel like I’d hear it but maybe not,” she said.

Guyger was arrested Sunday and ordered held on $300,000 bail, which she posted and has since been released.

Jean, who was an accountant, worked as a risk assurance associate at consulting firm PriceWaterhouseCoopers.