One Dallas police officer, who spoke to NBC Dallas-Fort Worth on the condition of anonymity, said Guyger had just finished a 14-hour shift when she returned home and took the elevator to the wrong floor.
The source said Guyger went to what she believed was the door to her apartment, but was actually Jean's. She struggled to open the door with her key, so she set down the items she was holding to focus on getting the key to work.
As she continued to fiddle with the key, Jean allegedly swung open the door and startled her. The source said Guyger believed Jean, who was only wearing underwear, was an intruder and shot him with her service weapon.
The source said Guyger didn't realize her mistake until police and rescue units began arriving at the complex. After she realized the mistake, the source said, she became emotional and fully cooperated with officers, offering to provide blood samples.
This version of events was later taken out of the NBC article, but the original story is in an archived version.