The Invisible Maniac (1990) on Netflix

Plot summary

Kevin Dornwinkle is caught by his mother peering through his telescope at a woman undressing, and she punishes him for it, condemning women as wicked. Twenty years later he is a scientist in molecular reconstruction who demonstrates an invisibility serum for the world's leading scientists. The demonstration collapses, the audience mocks him, and he murders four of them. He is committed to a hospital for the criminally insane and escapes, then is hired as a substitute physics teacher at a high school under the name Dr. Kevin Smith. The students are already arranging to harass their new teacher, and Mrs. Cello, the principal, makes advances toward him.