Dr George Kenney was given his orders by school chiefs in Florida as they launched an investigation into the 16-year-old's death.
The parents of the Wesley McKinley said they have a 'ton of questions' and want to know if the hypnosis had anything to do with their son's death.
The teen was found dead in an abandoned house from a suspected drugs overdose.
The day before he killed himself he underwent a hypnosis session with Mr Kenney, an certified hypnotist who has written a book on the subject.
McKinley, who was found dead April 8, told Kenney he wanted to focus more in school and be more outgoing.
The principal had hypnotised dozens of students in the last two years for those wanting to improve their powers of concentration for exams or sports.
Kenney said he always sought parental permission and invited parents to sit in on the sessions.
An investigation has revealed that McKinley, who had showed no outward sign of depression, got his mother's signed approval to take part in the session at North Port High School in North Port, Florida.
He had undergone three previous sessions with Mr Kenney having expressed a desire to be more focussed in school.
The possibility of link between the teen's suicide and the hypnosis came to light after students at the school began to question if it had played a part.
The dead boy's father said he has questions about his son's death. Read More