CSI: Miami Season 8 Episode 13

A motor-biker chases social studies teacher Russell Turner and cuts him in two with a samurai sword. The fatal katana is found at his home, wielded by his gentle, terrified adopted son Kenny. He found his dad's body but fled, having been previously told to hide for his life. DNA confirms Kenny is sakuru (Japanese mob) lord Takashi Yamada's biological son, born as Yoshi. Then his biological mother Susan Lee, who fled Yamada 15 years ago, fails to abduct the boy. The next crime has the grimmest motive.