Season 7: Episode 15 - Law of Gravity

Law of Gravity: Grissom returns from his sabbatical while Keppler is put into a compromising position when the bodies of a Trenton police officer and a hooker are found in a hotel room. Things do not bode well for Keppler after the discovery, causing him to act dangerously in his desperation to save himself. He attempts to cover up his past crimes, but only winds up burying himself deeper, and losing what little support he had.