function burnTokens(address _owner)
        public
        onlyCrowdsaleManager
        returns (uint)
    {
        
        if(currentPhase != Phase.Migrating) return 1;

        uint tokens = balanceTable[_owner];
        if(tokens == 0) return 2;
        totalSupply -= tokens;
        balanceTable[_owner] = 0;
        LogBurn(_owner, tokens);

        
        if(totalSupply == 0) {
            currentPhase = Phase.Migrated;
            LogPhaseSwitch(Phase.Migrated);
        }

        return 0;
    }