CHARLOTTETOWN- A Prince Edward Island cabinet minister has asked a law firm to conduct an inquiry into a village councillor’s decision to display a sign denying the existence of residential school graves. Communities Minister Rob Lantz issued a statement Wednesday saying Murray Harbour Coun. John Robertson had failed to comply with a ministerial directive to pay a $500 fine and issue an apology or resign, sanctions that were first imposed by the rural municipality. Lantz said that under provincial legislation, however, he couldn’t take action until an independent inquiry investigates Robertson’s conduct, even though the municipality has completed its own probe. As a result, Lantz has appointed Michael Drake, a partner with the law firm McInnes Cooper, to carry out an inquiry, saying such a move is unprecedented. “As a…