Wilton police arrested a Wilton man on July 30 on charges of sexual assault. Gaston \u201cAlex\u201d Acosta-Rua, 18, surrendered to police Monday morning on an arrest warrant issued by Stamford Superior Court. Acosta-Rua was processed and released after posting a $50,000 bond. His arrest stems from an investigation of a sexual assault of a minor earlier in the year, police said. Acosta-Rua was charged with two counts of sexual assault in the second degree, a felony, and reckless endangerment in the second degree, a misdemeanor. He has a court date of Aug. 10, at Norwalk Superior Court.