Director Deon Taylor stated he spoke with the family that was taken hostage, and having an "incredible conversation" with them about everything that went down. He didn't have enough time to speak with Scully, who was on death row at the time, so he "couldn't get an entire story". Taylor said he "solely went with the family's perspective" because it was all he could do.
Based on the real-life events of March 29-30, 1995, when white supremacist members of the Aryan Brotherhood took an African-American family hostage after having shot and killed a sheriff's deputy.
Officer Trejo was killed with a sawed-off shotgun, unlike in the film, where he is shot by a pistol. His service pistol was stolen from his corpse, which would explain the second gun Brenda is shown brandishing.
The bad guy "Garrett Tully" real life person is Robert Walter Scully who was sentenced to death June 13, 1997. He made several appeals and finally appealed to the Untied States Supreme Court for certiorari which was DENIED, Feb 22, 2022, ...25 years later(27 years since the murder). R.W. Scully is still on death row as of April 2022.
Scully was imprisoned in Pelican Bay Prison, Northern California.