Police say 47-year old Herman Tucker was shot to death inside a Motel 6 on Military Road in the early hours of September 7.
Witnesses say they saw Tucker enter the room, then they heard an argument and gunshots, according to police. Tucker then stumbled out of the room and died at the scene.
At least four people were seen running from the room just after the murder.
Detectives arrested the girl Wednesday at noon in the area of 23rd and Cherry in the Central District. They're now looking for 19-year-old Kavahn Matthews-Smith, who is also suspected in the murder.
Mathews-Smith stand 6'5" tall and weighs roughly 180 pounds. Police say he sometimes uses his twin brother's name, Keenan Mathews-Smith
Detectives say they'll likely make more arrests in the case.