Amber Guyger, the former Dallas police officer charged with killing Botham Jean in his own apartment, missed numerous signs indicating she was not on the right floor or at the right apartment the night of the shooting, a prosecutor said Monday.

The fourth floor of the garage where she parked after her 13.5-hour shift was open air, unlike her parking area on the third floor, Jason Hermus, a prosecutor with the district attorney's office, told jurors.

She failed to notice a skylight, a neighbor's decorative planter, Jean's red doormat and differences in the hallways, Hermus said. 

Once she opened the door to Jean's apartment, he continued, she didn't notice other differences, including a missing table, clutter on the counter and the aroma of marijuana, the prosecutor said. Jean had smoked marijuana to help treat his ADHD after he stopped taking his prescribed medication, which had an adverse effect on him, his sister told jurors.

But Guyger's attorney said she was fatigued from working, and was on "autopilot" when she parked her car and walked down the complex's nondescript hallway and encountered what she thought was a burglar in her apartment. The shooting was "nothing short of an epic tragedy," Robert Rogers told jurors. 

The former officer killed Jean in his apartment on September 6, 2018, believing it was her unit, which was one floor below, police said. 

She was indicted on the murder charge more than two months later. She has pleaded not guilty, and faces up to life in prison if convicted.