On Friday, prosecutors charged 18-year-old son Robert Bever and his 16-year-old brother, Michael Bever, with five counts of first-degree murder and other crimes.
Both brothers will make their first court appearance Monday morning.
Detective say the brothers acted collectively once they killed their mother and father, David and April Bever, and their siblings Daniel, Christopher and Victoria.
The two are charged with five first-degree murder counts and with assault and battery with intent to kill for the attack on their surviving sister.
Tulsa County District Attorney Steve Kunzweiler, whose office filed the charges, has said Michael Bever will be tried as an adult.
Booking photos of Robert Bever and Michael Bever.
Broken Arrow police have said the 13-year-old told them her brothers were responsible for the attack.
The assault charge alleges that the brothers used a knife to stab the girl “multiple times with such force that was likely to produce death”. A 2-year-old was also found in the house, unscathed. They credit one of the younger brothers with saving her life by making a call to 911 before he died. Leon Calhoun of the Broken Arrow Police Department, according to KFOR.