Nearly 7,000 Peace Corps currently serve in about 65 countries. Roughly one in five of them is sexually assaulted during that service, according to the results of a recent anonymous Peace Corps safety questionnaire, obtained exclusively by CBS News. The report also shows that nearly half don't report the assaults. More than 500 volunteers have reported experiencing a sexual assault in a little over two years. CBS News spoke with nearly a dozen who questioned how their recent cases were handled. They told us they ... were threatened they would be fired. Five years ago, the Peace Corps - a government agency - faced intense scrutiny over its response to sexual assaults. The agency's director at the time vowed change. I hired a nationally recognized leader in victims' rights to be our first agency's victim advocate," former Peace Corps director Aaron Williams said during a congressional hearing in 2011. That leader was Kellie Green. "I pushed the agency to really do what they have the capability of doing," Green said. Earlier this month, the Peace Corps suspended her without pay for allegedly creating a hostile work environment. But Green says she was punished for standing up for the victims she was hired to protect. Inspector General reports show multiple cases of Peace Corps personnel - accused in sexual assaults - resigning ahead of administrative action, then being allowed to re-apply to the agency. Green is pursuing whistleblower protection. The Peace Corps disputes ... that it retaliated against her.