Pinal County prosecutors declined to elaborate on the decision not to charge 27-year-old Logan Hackney and 25-year-old Ryan Hackney. The two were scheduled to appear in court Monday for a preliminary hearing.
They were arrested March 15 for allegedly failing to report their mother's abusive behavior toward five of her seven adopted children.
Machelle Hobson, 48, has pleaded not guilty to charges she abused some of the adopted children by pepper-spraying them, striking them with a clothes hanger and making them take ice baths.
She remains in custody on a $200,000 bond after entering her plea on 24 counts of child abuse, five counts of kidnapping and one count of aggravated assault. A pre-trial conference is scheduled for May 1.
Hobson is accused of using pepper spray on a child's genitals, applying a lighter or stun gun to a victim's genitals, arm or other body parts, and causing them to suffer malnourishment.
Hobson's biological daughter, who is an adult, alerted police of the abuse, prompting officers to visit Hobson's home in the city of Maricopa, about 35 miles (56 kilometers) south of Phoenix.
The Arizona Department of Child Safety removed the seven children from Hobson's custody and they're now in foster or group homes.
YouTube has since terminated Hobson's channel, which featured skits about children stealing cookies or a boy with superpowers, after determining the channel violated its guidelines.