TORONTO -- A 40-year-old Toronto teacher is facing new charges in a sexual assault investigation that now involves three female students.

Christopher Parkin was charged in April with three counts of sexual exploitation and one count of sexual assault after police investigated allegations from two female students.

Police say Parkin was re-arrested on Monday and charged with luring a child, invitation to sexual touching, and sexual interference, following allegations from a third student.

Parkin taught at Forest Hill Collegiate Institute in Toronto and police say the alleged offences occurred during the 2011, 2012 and 2013 school years.

Investigators say they fear there may be more alleged victims and are asking anyone with information to contact police.