Unauthorized Tenant - How long before they are considered gone

[Melissa N.]

One of our tenants let his girlfriend stay with him (she started getting mail there). He wanted her out and tried to get a restraining order to get her out but they denied it. He is partially disabled and has not been an issue before this incident. His grandmother helps him so she's been in contact with my property manager. 

He kept saying he was trying to get her out but after we filed a 3 day notice, he now says she's gone but she still has stuff there.  How long before she is no longer considered a resident? What documentation should we get from the tenant to state she is not a tenant, if any? (This is in Cincinnati)