Dr. Melvin Koss was Perri Grey's boss at Mergenterprises. When he encountered his intern about to show April O'Neil around the facility, he denied her access. As April was leaving, she witnessed Shredder's henchman Tim London delivering chemicals to Koss, and she became suspicious. Later that night, she returned to Mergenterprises, where Grey was also investigating Koss' behavior, and they saw him working with the evil Grem aliens. After the defeat of the Grem, however, it turned out that he had been brainwashed by them. The Fifth Turtle
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