Squatter/ unlawful detainer/ eviction

[Nicolas Pretelt]

Hi,
I have been dealing with a 'squatter' eviction, and I wanted to find out about everyone's opinion:
I already have everything set up with the title company: purchase & sale agreement, pay off letter, end buyer etc.
I am just waiting to evict the squatter.

The squatter is an ex boyfriend of the property owner. He the squatter has never pay rent, does not have any tenant-landlord documents,and his name is NOT on the deed but has been living in the property for the past two years by himself and for 10 years together with the seller.

The Case is now being handle by my lawyer who is recommending to file an unlawful detainer, while the squatters lawyer is arguing that his defendant has rights on the property like compensation, or plain rights to the property

What are your thoughts? Should I file unlawful detainer? Does the defendant have any type of rights?
Thanks,
Nicolas