Accused Of Sexual Assault

needing help asap! my little brother is being accused of sexual assault. he’s a minor, and my mother was called by a sheriff and asked to come in today for questioning with my brother. my brother says he hung out with this girl a few times, they decided to have consensual sex, he then called it off with her and now he is being accused of rape. i advised my mom she should probably have an attorney and have him not answer any questions. my little brother is anxious just to speak with the police, show them text messages proving he is innocent, and clear his name, but i’m worried this will hurt him more than help. we cannot afford a lawyer. would it be best to tell the police he doesn’t want to speak and ask for a state appointed attorney since we cannot afford one, or if he’s truly innocent should he just speak with the police?