Wisconsin month to month lease question

[Brad Perkins]

Hi! I recently purchased my first duplex in Wisconsin. We will be moving into one unit and the other unit has a tenant. This tenant notified us on closing day that he planned on moving out at the end of the month. The lease he signed in 2014 is a month to month lease that requires a 60 day notification before moving.  The current tenant is saying that after a year on the lease, he becomes a periodic tenant under Wisconsin law and it only requires a 28 day notice.  I cannot find this anywhere, but also am new to this so we are still discovering the ins and outs of landlording. Can any Wisconsinites help me out here? Sorry for the long question!