My son's father (my ex) is being accused of molesting is 9 year old daughter (my son's half sister). DCFS questioned my son on his father about abusing him. They came up with nothing, saying he was not abused. How can I really know. My son is a very angry child, but also is very close to his father. My question is how do I really know? And should I get another opinion?

Discuss your concern with a child psychotherapist and let her examine and treat your boy. His anger is reason enough to ask for help.