Kazuo Saki was a detective of the Tokyo Metropolitan Police Department and younger brother of Oroku Saki. With the Turtles' help, Kazuo investigated his brother's crimes. Shredder handcuffed his brother during a confrontation, but he was rescued by the Turtles. Kazuo defeated Shredder by throwing him into the portal.
In most incarnations of the series, Saki is the given name of The Shredder, and Oroku is his family name (as evidenced by his brother in Mirage Comics, Oroku Nagi.)