To remove a person from real property, an owner will use ejectment, unlawful detainer or eviction.
Eviction is only for tenancies, and this situation does not fit.
Ejectment is a broader lawsuit, is filed in circuit court, and costs a little more (about $100.00 more).
Unlawful detainer is narrower, filed in county court, and is a little cheaper.
The property owner should seek a local landlord lawyer who will look over the facts and decide which way to go.
In the meantime, the property owner can serve a notice that states the property owner no longer wish the occupants to be on the property and must remove themselves immediately. Place two copies on the front door and mail two originals certified mail return receipt requested to the property address. Keep four copies for your file.
All property owners should sign the notice. If you are unsure as to who is on title, go to the county property appraiser's website.
You can tell the son (although you are not obligated to do so) that he is not a tenant, so the 30-day rule he heard about does not apply. He must remove himself immediately. He and the girlfriend can be sued for the costs of the lawsuit and attorney fees.
Give 30 days notice--simple. Clean. Effective. Lawful.
If he refuses to leave--file the unlawful detainer--just as for any other tenant.
His kin relationship does not affect his status or rights as a tenant or the mother's obligations under the law as the 'landlord'. At least not on the facts you provided.
If mother is being threatened, she should call the police.
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