Employ someone, have them meet with the team they work with, either in person or at a controlled office, and have team meetings with them.

That proves the person you know was in the country you expect them to be, and eliminates the whole "local person pretends but the work is done by remote". The meetings mean they are available when you expect them to be.

Now sure they could have somehow got to the expected country to do that original laptop pickup, but you've got bigger problems if they are a spy and living where you expect them to be, and things like turning up to office every day for 8-6 isn't going to stop them.