dr donald dewitt , 65 , veteran teacher at bergen county academies in new jersey , charged with attempted sexual assault and criminal sexual contact .
dewitt , who is married , has been at the top-ranked school since 1992 , teaching biology , physiology and anatomy to juniors and seniors .
prosecutors say dewitt 's lewd emails to 16-year-old victim were discovered this week by her sister .
dewitt has been suspended from his $ 105,000-a-year job and banned from campus .