it's been a few days and i haven't found any sign of him, i've heard he has a range that he could come back from but i'm not sure how much of a range it is
Look outside the windows of your base, all of them. He will appear and you can get him back :)
(The upstairs windows first, preferably.)
i tried that, all i saw was some red blob for a second through the admin room window and a blood stain on the other side, still no sign of kerfur