PINE RIDGE, S.D. -

Federal authorities have charged and arrested the grandmother of a 2-year-old boy allegedly killed by his mother on the Pine Ridge Reservation over potty-training issues.

Forty-seven-year-old Sonya Dubray is accused of hindering the investigation by altering or destroying evidence and giving false and misleading information to investigators.

Dubray faces charges including accessory to murder and tampering with evidence. She was arrested Monday and is due in court Wednesday.

Dubray's daughter is 28-year-old Katrina Shangreaux, who has pleaded not guilty to murder and child abuse in her son's late-July death. Her trial was recently delayed from early October to early December.

The boy was the half-brother of a 1-year-old boy who authorities say was slain in April 2015 by the father of the two boys. James Shangreaux has pleaded not guilty.