Pickett was due to go to trial Monday on a charge of second-degree murder while armed
Pickett, who was 26-years-old when he was arrested in March 2011, told authorities that he accidentally shot McGee at their Southeast D.C. home.
At a preliminary hearing in the case, Detective Carter Adams testified that Pickett said he and McGee were arguing and he decided to stay the night elsewhere. While packing his belongings he picked up a gun and accidentally fired it when he was pushed or he tripped.
The bullet struck McGee in the shoulder, killing her, authorities said.
Sentencing is scheduled in the case for Sept. 14.
Plea documents have been added to this post.