This phrase is first spoken by Scully in conversation with Mulder after the post mortem on Owen Sanders, the fourth missing man. Mulder later throws the same phrase back at her in frustration as he leaves the Mt Zion Medical Center (where Aboah has been examined) to meet Diabra, the Burkinabe diplomat.
This phrase is first mentioned by Scully in conversation with Mulder after the examination of Owen Sanders' body. The phrase is later repeated by Mulder in response to Scully's frustration as he leaves Mt Zion Medical Center to encounter Diabra, a representative from Burkina Faso.