Raye Penber is an FBI agent who has travelled to Japan on business to perform a clandestine investigation into Light Yagami as L's number 1 suspect on a hunch. He's an eager worker and has quite the potty mouth. He takes his job so seriously he looks like an idiot as a consequence. For a voice I'm not looking for anything particularly goofy, however. A simple adult male voice contrasted with his behaviour will form his character rather nicely.

Ray Penber only has 1 line for episode 2, however he features prominently in episode 3. (spoiler for the original series) If you're familiar with the official release you know that Raye of course dies soon after his first appearance. When you are cast for his role you will of course have first access to auditioning, or being chosen for any future roles that arise later in the series.