OTTAWA -- Police say an Ottawa man faces 11 charges after an investigation into allegations of historical child sexual assaults.

Ottawa police say the investigation began in June 2016 when someone came forward with allegations.

They charged 75-year-old Donald Greenham on Wednesday with offences including gross indecency and indecent assault.

Police say the allegations involve a time span in Ottawa of between 1972 and 1981 when Greenham was a teacher and coach with the Ottawa-Carleton District School Board.

The charges relate to allegations involving four male victims between the ages of 12 and 16.