Ok, that confirms that the person owns the database. Chances are they created the database initially since SQL Server will make the database creator the database owner and many people do not know this or do not bother to change it.

SELECT SUSER_SNAME(owner_sid) as owner_name

FROM sys.databases

WHERE name ='YourDatabaseName';

You can use ALTER AUTHORIZATION to change the owner to sa if you wish. Some precautions should be taken if cross-database ownership chaining is being used, or if the Login in question needs access to the database going forward and is not in the sysadmin Group or does not have a stand-alone User in the database.