Property manager signed 12 mo lease instead of mo to mo as agreed

[Bette Grace]

When I signed on with a PM, I told them I wanted my house rented month to month.  I recently listed the house, and found that the PM signed a 12 month lease with the tenant.  The tenant falsified their application by not listing their children as residents, and did not pay utilities for 4 months.  Am I right to assume there is no valid lease?