A good roll on a social interaction could drop the hint that his accent isn't right for the region he is claiming to be from. Also if they see a video of the dude talking, or get a call from him, etc... as long as they hear him/her speak. Then a perception roll or whatever you chose to make it, and as long as they succeed you can drop the hint. Higher levels of success could provide greater insight into narrowing down the region he is from. Perhaps, in addition to the accent, he is wearing a head scarf that is common to X region, or he said something about an indigenous species (or one passes in the background of the video), or hearing the roar of it, off the screen, background noise. A triumph could single out the exact solar system, or planet. These are not the only ways about it, but they flow well with the story and provide something of a limiting factor.

Beyond the starting hint, it's on the players to pursue it further.