Where are most of his belongings, his family ties, where does he intend to return to when done with this assignment.

Who issued his driver's license? Where does he vote?

Do they own a house in NY?

What do we have the FBI doing in Canada?

I think we have FBI all over the place.  The only difference is this one didn’t have to spend as much time learning a foreign language as some of the others.

Unless he is in the part of Canada that speaks French..

We-we.  Or is it wi-wi. Or wewe?  wee-wee?  Wiwi?  Weewee?  Why did you have to go and complicate things?  Eh?

He has a NY drivers license,. and he votes in NY . He does not own a house. He was renting in NY and moved all his belongings to Canada.

He took all his belongings with him. He will probably return to NY when the assignment is done.

I would go with NYS resident. It meets the domicile test.

And NY is one of the tough states when it comes to proving you abandoned residency.

I agree with @Camp1040 

Keeping a PO box in NY sure doesn't help when you are trying to say you abandoned the state.

Let alone drivers license and voter registration.