[saboot]

If you are under surveillance it's likely they would have observed this already. Don't assume they would go beyond removing all of your valuables and clothes right then and there if they thought this setup was in place.

Some of the above methods can still be broken. Requiring a face present? Why not just print a big blowup photo and quickly insert in front of camera?

There are smart people getting around security.

[Pinatubo]

It's hard to imagine they could simultaneously arrest and restrain a guy, while keeping him within 3 feet of his laptop, while preventing him from shutting the lid or locking the computer. Falling to the floor would be enough to break the connection and lock the computer.

[MichaelGG]

If they're already in your house, then it's probably game over. Otherwise it should not be detectable to a third party observer that you have a small transmitter in your wrist bracelet.