Amit Kanse and his father Satyam, Ravindra Kharte and his father Madan and Rinki Jhauvri and her father Ramprakash, all residents of adjoining Dewas district, are being questioned after their arrest, police said.
Amit and Rinki are students of Mahatma Gandhi Memorial Medical College, while Ravindra studies at Bhopal-based Gandhi Medical College.
The scam was exposed by the Indore Police on July 2 last after arresting a number of people, including three officials of MP Professional Examinations Board, responsible for conducting examinations for various professional colleges.