The Brief Chester County investigators are asking for help identifying possible victims in a sex assault case. Chester County investigators are asking the public to help identify possible victims in a growing sex assault investigation, according to prosecutors. Investigators seek help as new evidence emergesProsecutors say Rosa was charged in April with possessing child sexual abuse material. If you or someone you know has spent time with David Rosa, please contact the Chester County Detectives," said Christopher de Barrena-Sarobe, Chester County District Attorney. Rosa remains held in the Chester County Prison, according to prosecutors.