had finally come to an end. but then, a knock at his apartment door. it was a police detective. and he had with him this piece of paper, an anonymous fax, charging karl ryll with keeping large amounts of date rape drugs in his apartment. >> and the fax also said i was giving these to my female students in my classroom. >> reporter: could you think of a more serious -- >> no. i'm not tenured. and any hint of any impropriety whether it's true or not, i mean, that would follow you the rest of your life. >> reporter: career would be over? >> yeah. >> reporter: karl says as soon as he saw that fax, he knew who it came from. what did you think as you read that letter? >> i was shaking. because i'm, like, i knew right away standefer did it. i told the police, i know who did this. the police questioned karl, searched his apartment, left without finding any evidence.