On December 26, 2017, 27-year-old mother of four Tanganica Wallis was fatally shot during a domestic altercation at a home in Terrytown, Louisiana. The argument reportedly involved Wallis’s mother and Wallis’s ex-boyfriend; Wallis stepped in to try to de-escalate and the situation turned physical.

Authorities say the ex-boyfriend’s sister, 28-year-old Raina Johnson of Harvey, allegedly produced a firearm and fired, striking Wallis. Deputies from the Jefferson Parish Sheriff’s Office responding to shots fired found Wallis with a fatal gunshot wound; she was pronounced dead at the scene. Johnson was taken into custody in the home and was later charged with second-degree murder; the suspected firearm was recovered where the shooting occurred.

What details about the events that night or the relationships among those involved could help explain how the argument became deadly?