CSI: Miami Season 7 Episode 4

Dying from stomach stab wounds, Russian extreme fighter Vince Koslov stumbles into Forest service employee Daniel Nash. Koslov bit off a tattoo from his presumed hit target, Russian mob burglar Andrew Brodsky, who is found bled to death but didn't touch the fatal knife. The knife traces to diving equipment salesman Greg Donner, who sold it to Brodsky's girl Cassandra Gray. She falsely confesses to the stabbing, apparently under the duress of a death threat from the Russian mob. Horatio believes that Ivan Sarnoff's fight club is actually a Russian mob killer training program. He finds in the club the blood of corrupt yacht owner Nathan Madden, missing since two years, according to wife Susan. But how does it all tie together?