A Pine Ridge woman is accused of killing her 2-year-old son, whose father is awaiting trial in the death of another boy last year.

Federal authorities say the son of 28-year-old Katrina Shangreaux had bruises and bite marks on his body and a torn scrotum. Investigators believe a potty-training issue triggered the alleged abuse and killing in late July.

Shangreaux is charged with first-degree murder and could face life in prison if convicted. The Associated Press requested comment from the federal public defender's office, which is representing her.

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 is to stand trial in January on murder and child abuse counts. He's pleaded not guilty.